Keep in mind that the walls are pretty flimsy and probably wouldn't be able to bear much weight without reinforcement. Your best bet would be handles to the floor.
The wall to the left of the toilet (as you are sitting on it) does have the waste tank vent line and some electrical lines running through it so you'd want to be careful about that as well.
In your spare time you may want to peruse though this thread:
Axis/Vegas Mods...1,2,3 Go.
For other ideas for Vegas mods...