One way to reduce the number of items on the panel is to use push-on, pull-off type circuit breaker and use it also as the power switch where appropriate. For example, pushing and pulling a breaker to control a landing light seems quite reasonable, or to control any other lighting circuit for that matter. By grouping branch circuits that would normally have on/off switches together, one might consider using the push-pull type breakers to accomplish both the circuit protection and the circuit control tasks.

No breaker manufacturer will recommend that you use their standard push-pull breaker in this manner because they are not rated for switch service. Switches are usually rated for tens of thousands of operations. However, push-pull breakers are rated for 1000 operations as a breaker and still remain in spec. But consider this: how many flights will it take you to wear out a breaker that goes to pot in 1000+ cycles?

These parts could be placed on a replacement schedule as required.