We have a similar problem. The original convection oven installed by Airstream was a piece of garbage. It was replaced by the dealer with a Panasonic Genius. it is an older model but we werer familiar with Panasonic. I was concerned when we started out in early May this year but now we are in Victoria BC Canada and it is quite a bit cooler so we welcome any spare heat.
I would not insulate in your case (Texas) but try to ventilate the space from the other cabinets on each side. I am still considering drilling holes in the side walls of the cabinets on either side. I have the kitchen sink cabinet on the left and a set of drawers on the right. I even considered installing a fan from a computer or similar
12 volt fan.
hope this helps
happy trails Norrie