I think it took me longer to figure out where I wanted to mount the radio then it did to actually mount it. I'll apologize in advance for the long winded post, but figured I'd give as much detail as possible in case anyone else wanted to do the same type of mount.
Anyway - Radio is a Uniden Pro 520XL, it's about the smallest CB other than the Cobra 75WX that I could find. (I didn't like the Cobra)
I didn't want to install it under the passenger side dash as I wouldn't be able to see it while driving. There wasn't any place in the dash to mount it without it sticking out and looking funny.
I really wanted to mount it to the ceiling just to the rear of the dome light. I took the plastic trim off the front bunk cutout and found out that the Chevy van roof is only a single sheet of steel at that point. I didn't think driving sheet metal screws out through the roof was a good idea.
I came up with a way to mount the radio, which weighs under 2lbs, by making a L shaped bracket out of some sheetmetal that I had. The sheetmetal (I think is was 12 ga) was stiff enough that it wouldn't flex. It already had a 90 degree bend in it so I just trimmed to fit. It's 5 inches wide and 7 inches long on the long leg of the L. The short leg is 5 inches wide and 1 1/2 inch high.
I held the radio up to the ceiling to see where I wanted to mount it. Once I had that location I measured back from the center of the radio mounting bracket to the aluminum crosstube in the coach frame in the front bunk cutout.
I got two nail in T nuts from the big box store that take a 1/4 inch machine screw.
The headliner insulation and cover is 3/8 inch thick so I had to take that into account. I wanted the radio mount bracket to mount solid to the sheet metal bracket I made and the insulated headliner was an issue. I got two nylon spacers from the big box store that are 3/8 inch high and 1/2 inch wide. The hole in center was only 1/4 inch so I had to drill it out to 5/16 to fit over the outside of the T nut.
I epoxied the two T nuts and spacers in place. The T nut from the top of the sheet metal bracket and the spacer from below.
I held the L bracket in place and marked the headliner where the spacers were. I used a 1/2 inch forstner bit and ran it in reverse (to not snag and rip the headliner material) to cut two holes for the spacers. I slid the sheetmetal bracket in between the headliner and the roof of the van cab and the spacers slide into the holes I cut in the headliner. The bottom of the spacers were flush with the headliner. I used sheet metal screws to attach the short leg of the L to the cross tube of the coach frame. I also added some 3M UHB tape to the top of the long leg of the L to grab the roof and keep the radio from bouncing.
The 3/8 spacers worked perfect and the CB mounting bracket snugged up tight to the ceiling when I put the 1/4 inch machine screws in. I cut a 3/4 inch hole above the dome light with another forstner bit running in reverse and put a plastic grommet in place. I mounted the antenna to the left front fender and ran the antenna cable and power wires up the A pillar and above the headliner to the grommet. Hooked everything up, checked the SWR and tuned it (1.5) and cleaned everything up. I can listen to truck drivers talking to each other on the interstate 4 miles away like they were sitting next to me so I'm good to go. It's just my wife and I in the camper and we leave the front bunk mattress in place all the time so the CB is out of the way. I've only hit my head on it twice so far.
It's easy to reach from the driver's seat and I can see what the channel number is without any problem. I can find the volume, squelch and RF knobs without looking so I won't become a distracted driver.