Most 4X4 Jeeps can be towed four down without modification.
In fact, most 4X4 anythings can be towed four down IF the transfer case has a "Neutral" position.
IMO, the Owner's Manual is the final authority. When in doubt, read the instructions. If the book doesn't have any instructions about towing, the vehicle probably shouldn't be towed.
Of course, there are ALWAYS exceptions.
CM1, USN (RET)
2002 Fleetwood Southwind 32V, Ford V10
Toad: '06 PT Cruiser, Kar Kaddy dolly
Toy (may become a toad): 2001 Dodge QC SWB, 360 Magnum, Auto, 4X4
"When seconds count, help is only minutes away!"
I highly recomend the Chevy HHR, lots of room and fuel mileage is great and can be towed 4 down. We went with the Chevy HHR after DW done many hours of research. We tow it behind a Mobile Suites 5th wheel. Just finished a 6,000 mile trip, not issues at all. Many miles were in Colorado Rockies. Good Luck with your Choice. GBY...