Fit windows with reflective bubble insulation. Works wonders. I can't explain very well what we did with the AC fan discharge, but think of it like a tent shaped piece that direct air flow more efficiently to the ducts. Increased the air flow a bit. Also insulated return air box inside and out like some have done on here. Used the same reflective bubble insulation and used spray adhesive to attach.
John and Rebecca Dickson
Emma-7 / Little John-5 / Iva-1
Full Timing Again, Rev B
2013 Ford F-350 Lariat CC LB PSD
2015 SOB TT - With OC's Awning Poles (#8)
At least in Heaven, RVs will be perfect, and I won't have to keep fixing them.