Ummmm wouldn't it be easier to just trim the whip?

Yes, but this is not what Ken was asking. I gathered he wanted to leave the
whip at a length that would work in the CB band, and add a siple matching
network for operation in the 10M band.

I used to easily work Japan from my pickup in Portland Oregon with 25 watts,

When 10M is open you can work anywhere with just about anything. During a
recent 10M contest I worked all over the world using a 8' loaded dipole indoors
and 10 watts.

73 Gary N4AST