Just front to back rotating? I have always cross rotated, drivers front to pass rear and vice versa, pass front to drivers rear and vice versa. So far pretty even wear.
I agree with your shop, with the Mopar lift and a 1.5” spacer the caster will be very low, also a lot of axle shift with that much lift and the oem track bar.
I have seen the issue you describe but only if I park it and then restart it in a few hours, if overnight and below 40 it reads the correct temp and has the seat and steering wheel heater on.
EAG makes a pretty decent looking one and has the sensor holes. Appears pretty solid and well made.
EAG Off-Road Rear Bumper Full Width with Parking Sensor Bracket Fit for 2020 2021 Gladiator JT https://www.amazon.com/dp/B08D7JJLQQ/ref=cm_sw_r_cp_api_glt_fabc_BTZERXKKSH7SJJX89KTP
Get a couple can of Fluid Film and spray all the bare metal it will prevent them from rusting, there are a lot of bare metal items under the hood worth spraying as well.
Yup, the Rubicon also comes with metal side bars that are around $400 with the brackets to install them on a non Rubicon so that plus the bumper are pretty close to $1000
Oem is pretty expensive especially if you want the side bars, probably around $1000 all in. Aftermarket would probably be stronger and cost a lot less, I am sure you could sell your Oracle backup lights to recoup some of their cost.
If you adjusted the track bar and recentered the front axle you probably just need to adjust the drag link to center the steering wheel as it will affect it when the axle moves.
I would go with the oem steps that come on the overland, they will do a better job of keeping the side of the JT clean from tire spray and won’t ever rust, they work very well as steps for my wife and daughter.