You want to snorkel the Wrangler so you can drive in over-engine water, correct?
Hope ya know that you need to do some mod.'s on the engine also, if you going "down under" [sorry, couldn't resist, mate].
On the mod.'s I 've seen and helped with,
1] The snorkel becomes the only, repeat, only air intake for the breather. Otherwise, you have to block off the other intake, prior to submerging.
2] point the front of the snorkel, outside of the vehicle, to the front of the Jeep. Put an airscreen over the opening. Why? You force air into the snorkle when driving, [somewhat like ram-air, but not quite], and that helps air intake. That also puts the air intake into anything in front of it. A small-mesh screen will assist. Also, a girl's nylons over the screen, helps out with the smaller particles. And, I would hope your girl doesn't mind you taking her stockings?
3] Now that that is explained, to the engine. You may want to get several splash shields, or have them fabricated, to protect the front pig, minimize splash into the fan and drivebelt, AND, to cover the coil, distributor and much wiring.
Whew, I hope I was right in that you are running high-water, otherwise, I sure spent some time on this post, LOL.
BTW, a snorkel will not increase gas mileage, actually it will reduce, but so minimal as not to worry.