2mtr and 10mtr you can get "No Ground Plane" antennas, Diamond makes the 2-mtr version and Radio Shack the 10, I put the 2-mtr on one of the arms for the VELMAC mirrors on mine and on the 10 mtr it's jamed in beihnd the couch INSIDE the rig (Fiberglass does not block rf) SWR on the 10 mtr antenna per the cobra is 1.0/1 Which is not only not bad, it's perfect.
2mtr is not quite as good (like 1.1 or 1.2/1)
ON many rigs there is a handy hole in the brackets holding the hitch receiver, You can extend the rail out by adding a single bolt to a properly cut and bent piece of metal and mount an antenna there. One on each side.
For other antennas, consider no-ground plane designs. One such design is a dipole A dipole antenna needs no ground, in fact it works best if it's a mile or so above the ground (rather impractical) but 20 feet is good and 20 mtrs you can hang a full size dipole on the average motor home. I use a Sunsetter flag pole, drive on base, 25 feet
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