Plumbing setup questions

[jjhwick119]

So I've started framing, and want to go ahead and run my pex and wiring through the sides so I can slap some walls on the bus. Got a few questions.

So below is my layout (modified a little since this, but not plumbing stuff) and the shower will be at the rear of the bus, 4 feet from the back wall. The water heater will be in the garage sharing a wall with shower about window level and vented out the side above the window(is this avoidable?). My grey tank will be below the shower. I was thinking about putting the fresh tank below the sink. That would place the fresh tank and water heater roughly 7 feet apart, having to then come 7 feet back up to sink. I'm not sure if I'd need two pumps for that.

Or, since this is an indoor unit, is it safe to mount in my cabinet to the left of the oven, vented to the outside. Its an rv oven, which will be built into a cabinet so there will be a few inches in between the two. Then it would be short run, and I can mount propane under under oven behind fresh tank and in front of the rear wheel for short hookups to oven and water heater. This would be my ideal scenario

Also, pump under the bus by tank?