that you've taken this step. I hope to hear you on the air soon mobile HF.
It is an awesome feeling to make those types of contacts. When I was riding shotgun on the "Ladies in 80's" run, I was able to make a 5-9 contact with a station operating a contest on the big island of Hawaii while I was at the top of (IIRC) Kingston Peak at about 12000' ASL.
I personally believe that this website is the most comprehensive mobile HF website around. It can be somewhat technical sometimes, but nevertheless, it is full of great knowledge that will, if followed, drastically improve your mobile station's ability and safety.
Check it out. If it somehow needs clarification, ask here.
My answer to the removal of the paint and rust issue was to make my mount out of stainless steel and weld it before paint. The other option I would suggest is to bare the metal and use dielectric grease like Butter Its Not
You need to read the section of the website entitled "Bonding" and follow it closely. The "antennas, commercial" article will also give you a head up on what not to buy.
There are actually antennas sold which are nothing more than a 50 Ω resistor with a radiating element (?) attached to one end. Obviously, they rate an F. One of these is the Maxx-Com. At $400 it is as costly as some screwdriver antennas.
The Comet HA-750BL is similar, but uses a very lossy, 6:1 impedance transformer, It is even worse than a dummy load if that's possible. It appears Comet has come to their senses, as the antenna is no longer listed on their web site.
Comet's UHF 6, shown at right, isn't any better. At less than five feet overall (72 inches with 80 meter coil), coils wound with #26 wire, it is the epitome of a dummy load on a stick.
The Diamond HV7A isn't a dummy load per sé, but it might as well be. Besides UHF and VHF, it covers 6 and 10 meters, plus one other HF band (40 and above). Its overall length is just 50 inches, and the coils are not just small, they're miniscule. The optional 40 meter coil is wound with what appears to be size #26 wire.
The Opek®, shown at left, shouldn't be called an antenna. With just 100 watts of power, the coil gets very warm after just a minute or two of operation.
If you buy one of these F rated antennas, you're throwing your money away.