I have a Yaesu FT857D. Remote control head is mounted to the dash bar of my Poison Spyder cage with a RAM mount and the power unit is mounted to a bracket above the passenger side rear wheel well (inside). I think there are some pics in my build thread.
The radio is 80m - 6m plus 2m & 440 MHz. It has dual antenna outputs so I run a 2m / 440 NGP antenna direct and a 102" whip off an FC-40 automatic tuner (mounted to the driver's side D-pillar of the cage) for HF. I also have an ATAS-120 antenna (not currently mounted), but have not been happy with its (lack of) performance on HF. It did fine on 2m, but that's a lot of bulk for just a 2m antenna. So basically, with the FireStik for CB as well, the back of my rig looks like an antenna farm, lol. Hope this helps. I can get pics of anything you like if need be.
Edit: No adverse affect on the Jeep from the radio, but I do have some alternator noise in my receive audio. If it ever bugs me enough, it should be pretty easy to fix with some chokes, etc. Never had a report of it in the transmit audio.
I like the idea of the unit being tucked in a water tight box while the faceplate is mounted in my overhead.
That sounds good on the surface, but cooling is going to be an issue in a water-tight box. The finals will need airflow over the heat sink.
Edit #3 for pics:
Not totally happy with this mount for the control head, but that's not a big deal. There are mounts everywhere.
I should probably add that I have installed Poison Spyder's C-pillar kit, so the pic below will make sense. This is the mounting location of the main radio unit . . .
. . . using this Molle bracket I found on eBay sometime before:
Here's the tuner for the HF antenna (had to fab the mounting plate myself -- that's why you'll see the Sharpie marks on it. It'll get painted someday.
And the antenna farm on the back of the rig is below. That's not the permanent home of the 2m / 440 antenna, but the bracket and coax were already in place from when I had the ATAS-120 there, so I used them. My plan is to replace the factory AM/FM antenna with the 2m / 440 antenna, then use a hidden antenna under the dash for the AM/FM. I rarely listen to AM/FM anyway, so if reception suffers, no biggie.
Under the plastic trim at both rear corners of the tub is a grommet for wires to pass from inside the tub to the area behind the tail lights. I used this grommet to pass the coaxes through from inside the tub and you can see the bulkhead coax fitting coming through the corner armor just to the right of the tail light. There is another one at the other corner of the tub, but I didn't see the need to show another pic. I thought this was a clean way to route the coaxes with minimal chance of trail damage. And if you ever want to disconnect a coax or antenna, just screw a cap on the connector to prevent water incursion. Of course, you have to be ready to drill a 7/8" hole through your tub, but since I had already butchered the taillight holes for the Crusher Corners that was no big deal to me. And the back side of the hole is in the void behind the taillights, not inside the tub, so you're not going to have an issue with water getting into the tub.
More info than you asked for, I know, but when you start installing your system, you're going to have a lot more to consider than just what radio and where to mount it.