The original walls in a doublewide are made to flex with the home. That's why you can't buy a new one with conventional drywall. The trim strips at the joints allow the movement needed. Unfortunately, this also means that a hard, rigid surface like tile usually won't work.
As far as removing or modifying walls? Well, by replacing what you had on the walls with heavier drywall, you may have already compromised the integrity of the home. These homes are not built to handle the loads of 1/2" or 5/8" drywall.
The same rule applies here when looking at walls in any other home, Assume all exterior walls are load bearing, assume all walls that run parallel to the ridge are load bearing and then get an engineer, a factory rep or a qualified contractor to look at your home and determine which walls are load bearing. Someone with a license and liability insurance.
I certainly understand why you didn't want to drywall your kitchen, The cabinets installed in these homes are near impossible to re-install after changing the wallboard. The cabinets are made as soon as the factory wallboard goes up and they're made to fit where they are. Often there are no backs in the cabinets and when you open the doors, you can see the wall. Anyway, when you take them down, sometimes they come down in pieces.
I wish I could be more helpful but without actually being there, there's no way Anyone can say which walls are load bearing.