Why not skip the incubator completely ? Or at least hedge your bet ?
If your native birds go broody so often, switch the carried eggs for the native laid eggs and let your local girls do all the work.
Save a few imports for breeding only- keep them apart from the locals to provide fertile eggs of known heritage, but put the eggs under the locals for hatching. That way you can choose breeds without regard for whether or not that breed tends to go broody- you've got the built in workers already.
Briing enough eggs to split the hatching chore- put half under broody hens and try incubating the rest. If you fail in the mechanical process, chances are your girls will bail you out. And you can get a local hen to adopt the newbees and raise them along with her own.
Good luck.