Several manufacturers offer long plates that allow a longer lens to be slid one way or another to find the best balance. The ones I've seen have all been of the Arca-Swiss dovetail type, so thats what you need to explore.
Kirk, RRS, Markins, Wimberley are just a few names that spring to mind. All will offer screw clamps to attach to the monopod and a couple ( RRS and Markins) offer lever clamps as an alternative.
If you choose to go for a lever clamp, stick with that manufacturer for plates as well. I tried to match an RRS lever clamp and Markins plate - silly boy, I only just avoided a very expensive accident when the plate did not grip at all and slid straight through. Screw clamps are more forgiving so mixing and matching is OK.