OK edited my post because I see where you mentioned what you were doing with the radios…
As for the CB radio, if you are pressed for space, take a look at one of these:
https://www.uniden.com/automotive/cb-radios/id-CMX560/CMX560_Off-Road_Compact_CB_Radio
I needed a CB radio for a long road trip a while back and I didn't want to clutter up the cab with a big radio mounted under the dashboard. Since my other radios are remote head with the RF decks behind the rear seat, this worked well. The connection between the hand held control head and the RF deck uses a 4 pair cable with RJ-45 connectors. I took an old category 5 network cable and used that to extend it. I added an old Motorola remote speaker I had and it really sounds good. Not the best CB out there, but it works well enough for what I do. You can step up to the CMX760 if you want some more features. For highway driving, listening to the truckers and others, a normal AM CB radio will work just fine.
As for the antenna install...
I did a 2017 F350 regular cab a few weeks ago.
No issues with aluminum. Using the right mounts and right antennas, you won't need to worry about "flexing" or any sort of long term damage unless you forget the antennas are up there and drive through a low parking garage.
If you want this to work well and last a long time, don't do compromise installations. Antennas work best when they have a good ground plane underneath them. Mounting off the fender, glass mount, on the bed rail, etc. are all good ways to screw it up. If you want this to work well, then putting two NMO mounts on the cab roof is the way to go. Aluminum isn't an issue, avoid anyone who tells you otherwise, you don't need that sort of negativity….
If you are going to use CB, then I would -strongly- suggest the Larsen NMO-27 antenna. It's a commercial antenna that can be tuned to cover the CB bands. It's not some consumer grade antenna that you'll pick up at a truck stop, you'll need to purchase it from a proper dealer. I've been using them off and on for 25 years now, no issues. If fact, the one I occasionally use now is 20 years old. I've put mine on my antenna analyzer and I was able to tune it for 1.3:1 SWR on channels 1 & 40 with a 1.03:1 on Channel 19. You can order these antennas with a spring at the base of the whip, but I've never felt the need for one.
http://www.theantennafarm.com/catalog/larsen-nmo27c-699.html
As for dual band, go with the lower gain antennas, they'll have more useable bandwidth. Personally I always used a simple 1/4 wave VHF whip since when I was running amateur gear, that's where I usually was. A 1/4 wave VHF antenna tuned for the 2 meter band will act as a 3/4 wave on the 70 centimeter band, so you can easily use it for both. They won't be quite as good as a dedicated UHF antenna, or a dual band, but where they really shine is the 1/4 wave antennas have a lot of useable bandwidth. I use them on my trucks. Very easy to use them across 144-170MHz with reasonable SWR.
If you do go with the dual band antenna, then the Larsen NMO-2/70SH is a good model. On the VHF side, it's 1/4 wave, so lots of usable bandwidth. Skip the gimmicky amateur grade antennas. Use the right stuff from the get go and you won't have to replace it later on.
As for the antenna mounts and other antennas, about the only other thing I can tell you is to not cut corners if you want it to last 15 years or more. There are a lot of Chinese made mounts and antennas on the market right now, and some of them are pretty crappy. Kind of pointless to save a few bucks by buying the junk, then having to replace it in a few years. Stay away from any name you cannot pronounce, and be aware that the Tram and Browning names are NOT the same companies that made CB radios back in the 60's and 70's. They are cheap Chinese antennas. Stick with the known good name brands, Larsen, Antennex, Laird, ComTelco, etc. Remember, do it once, do it right and you'll not regret it.
A few other things I can add based off the recent install I did:
As always, run power directly off the battery. Do not tap into existing wiring. You can connect at the passenger side battery and route it to the fire wall. My work truck has the 6.2 gas motor, so I was able to remove the air box, route the cable under there up to the fire wall. I mounted a 60 amp circuit breaker to the fire wall, just above the fuse box. From there, the wire (6 gauge) feeds through the firewall at an existing cable feed through. Down low below the fuse box is a large grommet. On that grommet is a bulb that sticks up. If you use a sharp razor blade, you can cut that bulb off and it exposes a hole in the grommet. I was able to get the #6 wire through there. It comes out behind the fuse box. From there I was able to route it over to the sill plate that runs under the door. If you pull the plate straight up, there is a wiring trough under there that will allow you to get the wiring all the way to the rear of the cab. I mounted the RF decks for my radios behind the seats. The control heads are under the dash. I mounted speakers to the panel behind the seats, one on each side. Makes it easier for my ears to tell which radio it is. VHF is behind the drivers seat, 800MHz is behind the passenger seat.
Ground your radios locally. Do not rely on the long negative power lead back to the battery, or the coaxial shield. Run a short jumper from the radio body to the truck body sheet metal. That can prevent a lot of issues, noise, interference, etc.
