leatherseats.com sells seat heating kits. I'd bet Katzskins does too. If you are removing seat covers anyway, may want to consider just buying new custom leather seat covers from one of those two companies. They aren't traditional 'covers', but full replacement seat skins.
I appreciate that you came from a Sport and, therefore, have a basis for comparison. I bought a Mojave and almost immediately switched to 35s and I thought it was totally fine. But had no basis to compare. Only once I switched to 37s did a need to regear become obvious to me.
It may bother you, but it does not bother your JT. It was born to be scratched, dented, bent and such. Those "damages" actually soothe the soul of your Jeep as long as there was no intent to damage but rather an intent to live as it wants to live. Your Jeep doesn't want to be in a museum or live...
Put 35s on my 2021 JTM soon after buying it new. The 4:10 gears seemed totally fine. I didn't notice a difference. Moved up to 37s a few months ago. Drives like it is wheezing (slower off the start, feels like it struggles. No pep in its step. Regearing to 4:88 next month. Going from 35s to 37s...
I'm in the same boat. I asked at a respected local gear shop and they told me labor is $1,200. He was happy to install whatever gear set I brought him, but warned me he only warranties his labor and not products brought by customers to his shop. He also told me I didn't need to buy a 'master...
I did lose some power after adding 37's (though the Geolanders I added are heavier than KO2s). Still is OK, but a definite difference. I plan to regear from the stock 4:10 to 4:88 this spring.
I've had 'em for 3 years on my factory rails. Work totally fine and create 0 problems. I used them maybe 20% I'd get in Jeep until I got my lift and 37s about 2 months ago. Now I use them 85% of the time.
Just buy a set of Drop Stops. Best $24 you'll spend. Work great: Drop Stop Auto Car Interior Supplies - Patented Vehicle Seat Gap Filler Set of 2 - Walmart.com