We have a 2" opening in our hitch and we bought a dual receiver, one on top of the other, and we put a bike rack on the upper one just like you are doing. Ours is quite heavy duty and I don't have any worries.
If I understand your post correctly, yours is the actual hitch on the MH, so I am not quite sure if I was of any help.
08 Itasca Meridian
Nissan Xtera Off Road