The cab in my Zforce is like a darn oven, gets so hot I don't like driving it. I've had the interior apart four times adding insulation. I've wrapped the front exhaust pipe with header wrap. I used 24"x36" welding blanket behind the firewall, removing the park brake assembly & seat belts to install - first photo. I ended up wrapping the parking brake & stuffing the seat belt cutouts with pieces of welding blanket to stop air coming in, unfortunately I forgot to take photo of park brake wrap before I put plastic cover back in. The plastic still gets really hot, even the bottom of the drivers seat. Blocking air at park brake & seat belts, along with a weld blanket just draped over the rear firewall behind the seats (second photo) has has reduced heat enuf to where I finally enjoy driving the machine.

I have an Alpha Glass D.O.T. windshield. I ordered tilt out windshield hinges for 46-49 Jeep CJ-2A. Will mod them to fit. I don't want to tilt windshield all the way up, just open it up a little for better airflow over built in vents.

[2015 Z Force 800 53/Trail EPS]

It all counts...and helps. I was surprised to find on mine that the gap between the firewall and the front plastics also extends all the way down the sides behind the front fenders. I used some cut strips of 3"x3" memory foam along the top to the sides but then I could still feel heat from the radiator coming in down the sides...so..more was added. A bit tougher to do but worth it. That and all the other things made mine also...not so bad to drive in warmer weather.

I thought the heat may be coming from the radiator thru the center tunnel, so I rolled up a welding blanket to fill the gap. Still had hot air coming thru park brake & seat belts, photo attached. I then added a 2nd welding blanket horizontally behind the firewall, full across. Still hot air. That's when I wrapped park brake and filled seat belt cutouts.

[2015 Z Force 800 53/Trail EPS]

I plugged all my holes too and just put a cheap boot on my parking brake.

It looks like your shifter boot has a frame around it to hold it in place. The shifter boot I bought didn't have that. I gorilla taped it to the underside of the tunnel  Unfortunately it didn't help. Glad it worked for you!

I added another welding blanket, overlapping the first one. HUGE difference! Now I'm getting hot air around my feet, the faster I drive, the more hot air. When the radiator fan kicks on, yet more hot air. I blocked off the big gap around steering shaft the best I could. I put a strip of foam between the frame & body panel where the fuse box is. I have no idea where heat around feet is coming from.