The size of the lift won't cause you MPG to drop, the size of the tires will.
If money is a concern do a 2 inch budget boost and if still want more lift add a 1" body lift. If you want it to do better off-road get some sway bar disconnects.
I have known a few people running this type of setup with 33's and thing worked just fine.
If in the future you decide you need/want to go bigger or better you won't have much money invested. The 1" body lift is a good mod for any Wrangler, built big or small.
Schitzangiggles: We used to teach our children to fight evil, now we teach them that fighting is evil.
2001 TJ, 33 trxus MTs , W, locked, belly up, some armor.
"If you aim at nothing, you will hit it every time." Zig Ziglar