Stew47,
Lots of good comments so far. I did not see any mention of the added insurance cost for the MH versus the trailer.
As has been mentioned, the power train maintenance on a MH can be substantial. Will it really be worth it for the limited use you plan?
Hard to say whether changing to a lighter trailer or more capable tow vehicle would be more economical and best suit your need for space in the RV. You did not say what about towing with the suburban you are not that satisfied with. Have you explored any upgrades to the suburban such as a Banks system, changing the rear end or better weight distribution/sway control system that might improve the towing experience?