The CB mag mount can be used on 10 meters by attaching a wire to the the shielding at the base then extending the wire to the side. There is always some length that is resonant on whatever frequency desired. On my particulat CB antenna the side wire was about twice the length of the vertical. Total length will be a bit longer than 8 feet (half-wave).
My very first contact as a ham was the Virgin Islands with this lashup taped on the roof of my motorhome.
Beside adjusting length I later found the up or down angle of the side wire can fine tune the SWR. The signal pattern will be stronger in the semi-circle toward the side wire... Perhaps half as loud as away from the side wire.
If you try to extend the side wire to tune 12 or 15 meters the feedpoint will be considerably off-center. The impedance will likley be over 150 Ohms, too high for your internal tuner to handle.
The down side is that 10 meters is so quiet now that few hams are trying to work that band. I now use a 20 meter version of that side-arm antenna and a 40-20-15-10 meter end-fed antenna for multi-band work.