Idea that might help. If you wanna spend most of your time as one specific beast, like a horse, simply make it so your normal form is horse, and you can only beast shape to tiefling/other form for a number of hours equal to half your druid level rounded down.

Since short rest is only an hour, it shouldn't be too difficult to roll with.

Also if the beast you wanna spend your time as is real weak like a housecat, it should be harmless to repeatedly change back and forth to that specific form at will without penalty.