Can't offer much advice in terms of what generator to replace it with or whether you should, but....As one thats also dealt with critter damage, I can offer you some insight on how we solved that problem.
We had critters crawl up onto the engine on our last Motorhome, a 36' Georgetown, and chewed up the fuel line. Smelled fuel really strong when cranked it up, so took off doghouse, and gasoline was shooting straight up like a geyser! Main fuel line had to be replaced. Found evidence several places inside of mice as well.
Was quite a challenge getting that fixed, because we could not even crank the engine without it being a huge fire risk, so it wasn't moving under its own power. Because of how it sits at the end of our long, narrow driveway, getting it towed would not be easy. Eventually, I found a mobile mechanic that came out and replaced the fuel line.
After that happened, I bought some mice repellant spray from Lowe's, and every few weeeks I spray that all around the Motorhome. I also spread rodent repellant powder (also bought from Lowe's) all around it to ward off other critters. Typically buy 3 or 4 cans of each of those a year, which is not cheap, but its a LOT cheaper than fixing the damage them critters can do!
Have not had a critter problem since.