My battery is not charging while on the tow vehicle or with generator. I have replaced the sold breakers under the frame still no charging of the battery

Congrats, you have found Ford's super secret fuse that drove everyone mad for years!

no info generic answer battery not fully charged or poor connections some vehicles have an access under ignition cylinder on column that a small tool can be pushed into to hit the release

If you are talking about a Dodge Caravan, the answer is: It depends on what you are trying to charge and how are you planning to charge it.
If you are trying to charge the battery, it then depends on the charger. If you want to charge the battery with the alternator by running the engine, then you can do so by running the motor whilst you are towing it.
(I did so with a 1985 Buick when I towed it from central Florida to central Ohio with the motor running.)
Be advised:
Unless you plan to disconnect the drive shafts, any vehicle with an automatic transmission should not be towed unless the motor is running.
If you are planning to use a plug-in-the-wall charger, you may need a loooooooooooooooooooooooooooooooooooomg extension cord.
God bless your efforts.

Without testing we'd only be guessing ! You have no idea of the complexity of the electronics on your vehicle . Replacing the ECM would mean a trip back to the dealer to have it programmed . Without programming your vehicle will never start . You had new battery an alternator installed , did it start an run when you picked it up. The charging system on your vehicle is computer controlled . DTC P0621
DTC P0621 : Generator L-Terminal Circuit
The engine control module (ECM) uses the generator turn ON signal circuit to control the load of the generator on the engine. A high side driver in the ECM applies a voltage to the voltage regulator. This signals the voltage regulator to turn the field circuit ON and OFF. The ECM monitors the state of the generator turn ON signal circuit. The ECM should detect low voltage on generator turn on signal circuit when the ignition is ON and the engine is OFF, or when the charging system malfunctions. With the engine running, the ECM should detect high voltage on the generator turn on signal circuit. The ECM performs key ON and RUN tests to determine the status of the generator turn on signal circuit.

Your best bet take it back to the dealer .

if you want to fit the tow bar your self you should be aware that by fitting a tow bar it is a modification to the vehicle and requires a certified plate attached to the vehicle to cover insurance requirements and road worthy inspections
next most purpose built tow bars sold by auto shops will pick up existing holes in the sub frame mand you can get a harness that piggy backs onto lights on one side for the trailer
Best talk with a tow bar retailer/ fitter as they can certify the bar and the fitment and have a harness in stock

In addition to Andrew's answer; check the age of your battery as they do not last forever. If a Walmart/Autozone, etc. battery, then they are typically good for 2 years and rapidly fail often without any warning.
Check the condition of your battery cables. They should be clean and completely free of corrosion (and that means the cables - not just the connectors, as battery acid can leach through the plastic cable wrap as if it were a hose).
Remove and clean all cable connections: Negative to ground if at frame, and frame to engine block (sometimes two different cables). Positive to power distribution box and to battery (again may be two different cables).
If all that is good, and it still acts up after charging, then suspect a dead or dying battery. FYI - the charging system can be tested for free at Autozone, Advance, or any other Auto parts store for free.
Best regards,

This is most likely an issue with the wiring harness going to the connector on your truck you need to start at the connector at the back of the truck and walk your way forward to the breakers under the hood (rarely is the 12 power on the trailer harness connecter simply fused since it is a higher current circuit, it usually uses a breaker just like your headlights). Before you do this find a copy of the wiring diagram for your truck so you know what you are looking for. Also a dead battery normally will not fully charge in the normal time span of a trailer being towed as you can typically figure over 6 hours to charge the type of battery (deep cycle) that is in a trailer.

If your plug to towed vehicle has an empty prong/terminal, add a charge wire from RV to positive on battery connection to towed vehicle. A lot of travel trailers have a charge line in the 7 prong plug to charge battery on tongue while driving. Be sure to include circuit breaker in line for protection and don't forget end at vehicle will still be live when disconnected from tow vehicle so make sure it is protected from shorting out against metal,other wiring etc.. If no extra prong/terminal on current plug, switch it over to another with enough terminals to accommodate it.

On those, you will need a pair of "tow tabs" that mount to the front frame. Same setup is commonly used to flat tow race cars. The bar will generally attach to the tabs with two pins with clips that keep them in place. Unless you are making the bar yourself, the tabs are sold with the bar. I have seen "rental" hook-ups that attach to the bumper but those are not very safe compared to a frame mount.

More than likely your looking at the towing package for wiring a hitch to your vehicle for towing a trailer. Probably can use some of that, but I'm sure if you stopped in at a GM dealer and explained what your trying to do, they'd have someone look & confirm for you that it's o.k. or not to use that harness, without a big service charge.