I was planning to make insulation panels out of reflectix. It's basically foil covered bubble wrap. Cut to fit. I'd consider some form of curtain between the front of the cab and the rear, that way you could crack the sunroof or something. Keep in mind that mosquitos are attacted to heat and co2, so if you plan to do that in the summer, you may want to make a screen.
The LC actually has air exhaust flaps built into the rear - that's what the little vents in the back do, so you may consider a low power RV fan that you can stick into the sunroof opening and running it on a second battery system.
In my actual RV, I installed one of these fans:
Amazon product ASIN B002N1J5IMAnd then added a PWM speed controller - the PWM is important to minimize power consumption. The one I bought isn't up, but this is basically the same thing:
Amazon product ASIN B071H2YQG5A little air circulation goes a long way.
Finally, being the nerd that I am, there's also some small vent fans, like this:
RioRand 6V 12V 24V 28V 3A 80W DC Motor Speed Controller PWM Speed Adjustable Reversible Switch 1203BB DC Motor Driver Reversing - - Amazon.com
Those can be installed and closed when not in use. Sunroof mount or you can make a hole...
This guy put some into his 'bugout van'
Ventline VanAir Roof Vent Review (DIY CamperVan) Tiny House Van
I had to laugh a bit, he uses the same dual fans I also have in my RV that I got for extra circulation:
Those are a hair loud but super flexible and cheap.
Edit: extra cheap but decent idea:
and
Also have to mention the screen with magnetic tape idea over the top for insect season.