Joseph, It's not easy going from AC to Dc current with the amp requirements of the 12V roof pumps. You will need a 120V to 12V converter which is capable of providing at minimum 10amps per pump. If you will be running two simultaneously, You will need a 20 amp minimum. They are approx. $175.00 or so for a 10 amp model. You will need to find out how much the converter can take as for continuous use!
Even though the generator is supposedly on sale, I wouldn't trust a $88.00 generator for such an important requirement. JMO, I would stick with a deep cycle or two wired in parallel.
Remember, It takes more to push DC power. It's why Edison lost out in the DC versus AC electric power bids.
A small generator will be nice for your lighting and such. As I mentioned in another post here, I run a 8D battery for my trailer needs and a separate group 24 deep for my Bandit. Sometimes it's a pain plugging in however, It's no-noise power and no fumes.
All the best,
Mike