Good Job! Looks pretty awesome!
Are you allowed to put bracing on the body? If so I would brace the steering rack shelf really well. Far as removing gears in the 42LE I am unsure if you could get away with that. Very sensitive transmission. Regardless it will just limp mode it and stay in 2nd.
If you went through the work to make the 300M bar work, you could use any bar really. I would love to see some picture however on how you have it hooked up! I'd imagine the full 1 in rear sway bar I have would help you but I am unwilling to let it go.