If your Jeep hasn't gone through an E-test this year, then go to any license bureau and get it registered as a diesel. This was a slam dunk for my Buick. If the renewal date is close, then would suggest to get it E-tested with the gasser. You have two years to renew plates so that gives you some time to do the conversion, but the change in designation must happen before your plates expire.
Hope this helps.
Bill
91 Buick Roadmaster/Avant 6.2 NA conversion (gone but not forgotten)
94 Cadillac Fleetwood (sold)
08 Aerolight 23TT
06 Vortec Max Silverado CC SB (sold)
10 Avalanche (electronic quagmire but love the truck)