It probably has tires with a higher silica content vs using carbon black. This is especially common in low rolling resistance tires but others can have it too. This isolates the car from the ground more (contrary to popular belief, tires don't actually fully insulate the car electrically) and then when you step out it discharges through you. Short of replacing the tires you could get one of those anti static ground straps like this and attach it under the car.
Here's an option for a solution
https://www.amazon.com/dp/B000CRBR8U/ref=cm_sw_r_cp_apa_glc_fabc_JJ23XDWG1X2FDPZCT956
Gates 90330 Anti Static Rubber Strap $7
https://www.amazon.com/Gates-90330-Static-Strap/dp/B000CRBR8U
It's static electricity, nothing to do with any wiring or circuitry.
The likely issue is that tires with too much silica don't ground the vehicle as well. Carbon black in rubber is a good conductor, silica is not.
https://community.cartalk.com/t/tire-static-electricity/61591
Just add a ground strap and call it done.
This may help: https://www.amazon.com/dp/B000CRBR8U/ref=cm_sw_r_cp_apa_fab_tneIFbVK6ZCRJ
Needs to be bolted to the metal frame under your rv.
Here is an example. This one does have a metal grommet to attach to the truck, but nothing through the rubber strap. I will take pictures next time I see one.
http://www.amazon.com/Gates-90330-Static-Strap/dp/B000CRBR8U