Insulation for sleeper/cab

Wasn’t sure where to put this, but I am looking for the best product/way to insulate my sleeper from the the heat/cold....but mainly heat, down here in South Texas.

I know Dynamat, but that’s more for sound deadening. I’m considering gutting my sleeper and remodeling it, but I really want to help keep that Texas sun at bay as much as possible.

Can anyone steer me in the right direction for insulating the shell of the sleeper while I have the panels down. Thanks

 

Yeah, I run the sleeper AC with curtains closed when I think about it. But, I don’t always think about it, and when that suns been beating down all day, the AC in the old girl can’t seem to catch up.

Plus, I’m just trying to ad more calendar days to nights I don’t have to idle.