"It sure takes longer and cost more then I originally planed for.

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Get used to that, It only gets better from here. Then again, you get what you pay for. So if you pay for the insulation now, you'll reap the benefits later. I'm not planning on doing this again, but who knows, so I'd like to get the best results possible.
As for the A/C issue, I stand firmly in the rooftop RV unit camp. The price is coming down on them and it's a "One and Done" deal.
www.adventurerv.net has 'em starting at about $400.00. You can get a heat strip as well, not huge 5000 btu, but probably all you need with all the insulation. See? Gettin' the benefits already.
Also, consider a good coat of Henry 587 reflective roof paint. I put a coat on Friday and the difference was remarkable. My trailer is white. but I could feel the reduced temp. from the Henry painted area vs the factory painted area. Totally worth the $40.00 investment. Easy application, too.
McDave