I'm not that familiar with RV stuff but I attempted to find something. It showed finding parts for a certain camper being hard as they closed and liquidated.
I think you should try this website big-manuals . It helps you repair your vehicle easily without more help. Ask the girl in chat at the bottom of the page
I could not find the capacity, but the manual says to fill to the appropriate level, not capacity provided. I would think the capacity for such pumps would be around 1 quart, give or take a little.
Why do you need to burn it for that long? If it is a small 'blow torch' style lighter they are only designed to be lit long enough to light a cigarette or cigar. If you need a flame source for longer periods of time you're better off using a full size blow torch.
The smaller cigarette 'torches' are small and made of lightweight parts. These can heat up the whole lighter. Possibly causing it to the burn the hand or even exploding!