You should be able to order a replacement tub. Just need to determine the part number. To install it should not be that bad as there is no back splash wall to remove and install. The worst part would be the lack of room to maneuver it around to get it in place. It might require removing the toilet. I have not looked really close, but there is a bunch of screws along the wall that need to be removed and then I expect the floor drain cap holds it down. I expect there would be something along the front edge to secure it to the floor, but have not looked close enough. The big issue could be are the nailers (wood to secure to) at the right elevation? You should be able to contact Jayco and ask for the wall construction drawings. You might have to play a communications game to get all the info, especially if you say you want to replace it with a high wall. Some customer reps I hear will send you what you want and others do not. Personally I never have had a problem.
One more thing to consider is the bathroom heating duct. May not be a big deal, but as I recall on the low tub units it is in a different location than on the high tub, not sure if the hole is precut or not.