Campaigns for planes with fixed radio frequencies should work better then. Spitfire and Mustang, F-86, Mig-15, Mig-19, etc.
In A-10C campaigns with lots of frequency changes (hi Baltic!) I preload the frequencies and then just switch the preselects. Another "trick" is to use the fixed views and to set one of them to the radios; then it's quite simple to dial the frequencies in (on autopilot or active pause).