Based on your dimensions you'd need 7 inches for your tow bar to be totally level. So since there's only a 6 inch and an 8 inch high low adapter the better choice is to have the sitting slightly higher on the RV side. If a tow bar pulling down on the vehicle front suspension it can cause tire wear issues as well as suspension issues so slightly higher on the RV side is best.
So the 6 inch # RM-048-6 is the best option. view full answer...
We do have the Roadmaster EZ5 Base Plate Kit # RM-521453-5 available for your 2018 Jeep JL Wrangler Unlimited. This fits as long as your JL has the standard factory bumper without a winch or guard.
For a compatible tow bar I recommend going with the Falcon 2 Tow Bar # RM-520 along with the coiled Safety Cables # RM-643 which gives you a great tow bar and safety cables rated for up to 6,000 lbs.
Please note that a complete flat towing setup includes a base plate kit, tow bar, safety cables,... view full answer...