The 76 Goldwing has only a 350 Watt charging system. I have added a few
things to the bike, like the CB, a GPS, a 90/130 Watt headlamp with high
beam modulator, 5 tail lamps, and a little air horn,
http://home.goldrush.com/obsoelyt/Horn1.jpg
http://home.goldrush.com/obsoelyt/Horn2.jpg
http://home.goldrush.com/obsoelyt/Horn3.jpg
http://home.goldrush.com/obsoelyt/Horn4.jpg
http://home.goldrush.com/obsoelyt/Horn5.jpg
It seems to be ok, so far, the horn compressor added 4 A to the system, but
doesn't run continously, and i understand an amplipfier doesn't use power
unless you have keyed down.
I think i am going to install a headlamp kill switch, I don't need them when
i am following someone, but usually i am in front navigating , and my new
horns may make that position permanent.
Plan 1017 on this page,
http://electronickits.com/kit/plans/cbradio/cbradio.htm
looks promising, but it's most likely snake oil.
This one also looks like it could be adequate for the job,
http://www.quasarelectronics.com/1017.htm '
But I don't know if 25-30 Watts is going to do the job, but a 4-5 Amp load
could be acceptable.
I will probably build 5 units for the people I regularly travel with, but
even having some that can hear only is ok .
Moving the ant to ground level doesn't seem practicle, some guys tow
trailers, and won't the bike block forward transmission? It would have to be
centerline mounted, these mountain roads are all curves. We do a lot of
400-600 mile camping weekend trips, and in August spend 2 weeks on the road.

Do you understand VHF-UHF vs HF?

Forget CB. It is old tech and needs ground planes and long antennas.

Use GMRS or FRS, it needs little or no ground plane and very small
antennas. Use the links Landshark posted.