Hi Randy,
I reached out to the manufacturer, and the thickness is .03 inches (about 1/30th of an inch) for the 30' x 9-1/2' Alpha Systems Superflex TPO RV Roof Membrane - White # AL32CV. view full answer...
Based on the part number you mentioned that would indicate you have a Coleman Mach RV AC unit so for a direct replacement AC unit solution you would want the Advent Air unit part # ACM135B that you mentioned as well as the Coleman adapter kit part # ACCOLKIT which allows it to plug right into the wiring you have on your RV in place of your current AC which will give you ability to use your current controls. view full answer...
Both the Replacement Motor # LG-196308 and # LG-142178 have the same mounting dimensions but, like you said the 196308 has a higher weight capacity at 6,500 lbs. The only other notable difference is that the 142178 has a motor speed of 5,500 rpm while the 196308 has a motor speed of 5,430 rpm.
I would go with the higher rated motor as it will last longer because it won't be working as hard. Just be mindful thought that if your landing gear is only rated for 5,500 lbs it will be your limiting... view full answer...