Twice I have broken a support arm (different arms) on our 1994 34 footer and had the same problem - how to get the bolt out. I am not sure if our rig is the same as yours but think they are pretty close.
I bent back the banana skin next to the step (see the picture) making a large enough entry to get a box wrench in and on the nut which is behind the skin. Then I used a hex wrench on the easily accessible bolt on the inside of the step. To ensure I did not lose the nut when the bolt came out I put some duct tape on the back of the box wrench when the bolt was almost out and the gently pulled the wrench and nut out. I could have rebent the skin but as it really does not show much just left it.
Same procedure putting it back together again. Hope this helps.
1994 34' Limited
2004 GMC 2500 HD