Meguiar's Direct NXT Generation® Tech Wax® 2.0 (Sold at Wal*Mart $15.00)
I usually keep white residue leftover type waxes away from black matte plastic surfaces for just that reason. The wax left a very nice appearance on Gel-Coat, Diamond Shield, regular painted surfaces and Chrome surfaces. I use it on all three vehicles: Honda CR-V, F350 and the MH.
I also use the micro-fiber towels for wax residue removal. Works great. Some use an Orbital Buffer (Might try that next time), but I just use the rags.
In-between waxing, use Meguiar's Quick Detailer to keep vehicle looking nice. I even use detailer after a couple days and it add an extra kick to the shine and smooths out the surface.
Here's something else... Hmmm,,, A bit much for a 45' MH, but have you tried Meguiar's Clay Bar System? I used in the the hood of the Honda CR-V and saw excellent results. You need to keep the suface wet with Meguiar's Detailer and wipe the piece of clay over the wet surface. Afterwards, apply wax, etc.
OK, while we are here, let's talk a second about using Carnuba wax. Carnuba wax 20 years ago was great, but even then it was short lived especcially in high UV hot climates since it would melt away quickly. When you see a can that may say: 100% Carnuba, that doesn't mean the whole can is 100% Carnuba. It means the small amount of Carnuba in the can is 100% pure. The rest of the can is something else, often bees wax.
Meguiar's NxT Wax is a good general purpose wax. There are waxes online that can beat it, but you'll have to shop and order online. NxT is easy to get at most auto-parts, Target, Wal*Mart, etc.
http://www.meguiars.com/faq/index.cf...51§ion=_51