Gus - you'll likely want to at least add screeing to the inside of both of those vents. Thanks for sharing your project and ongoing results.
I've got a PowerBright 2300 watt Modified Sine Wave inverter coming (should have been here yesterday). It is a compromise of power, cost, and reliability. Most reviews are very positive.
Wonder if there's a small residential model that would fit where our DM2862 is? Might have to lose the big drawer under it, though. Never know when it might give up the ghost and need replacing (so far it's working OK, though).
How is this conversion working for you now? I have a 2014 Landmark SA Edition and am seriously considering making the switch, more so now that I've read this thread and your experiences (and the suggestions/recommendations of others).