I have mine mounted on the top side of the rear roll bar drop on our 4dr using PT's bracket. The 10 lb fits perfectly with the hard top in place.
If you have a 2dr I think you could get away with running the bracket on the bottom side of the bar and still clear the seats.
I have been thinking about installing a C-Pillar kit, or using a clamp with a piece of tube to mount the tank more vertically under the bar. This would need to be done in the event that I decide to purchase a trektop.
Jason - KB0WLI
2008 Black JKU Rubicon
RIPP Stage 2, RockHard Bumpers, RockKrawler 3.5" X-Factor & Fox 2.0's, Nitro Sleeved, Artec Trussed & Gusseted, Synergy DL Flip, Energy green Spyder Louvers, 37x12.50-17 Falken Wild Peaks wrapped around 17x9 XD Addics