Nice report...I love mine too. It definitely bumps up the temp range on your gear although I'd say you were pushing it.
Regarding the insertion of inflatable pads/mattresses, I find it easiest when I partially inflate them so they still have some structure but can easily be bent and/or flexed. You may also find it easier if you insert the pad prior to installing the head end spreader bar. I push it part way through and then pull it the rest of the way from the other end.