It's a shame the system seems so 'up in the air'
The system is not 'up in the air', you are making a mountain out of a molehill.
If you are coming to the US on holiday and while you are here you want to rent a plane you don't need a visa. You don't need a visa to rent a car at LAX, a set of skis in the Rockies, or a hooker in Vegas. Europeans think flying small planes is a big deal, in the USA it's not. You will not be able to get time on a 747 simulator now, but nobody gives a rats-ass if you want to rent a warrior and putz around for a week or four.
If you want to apply for a tourist visa and spend money better spent on flying then go ahead. You don't need to, you are a British Citizen so can enter on the Visa Waiver scheme. Millions of Brits enter the US annually with no problems at all, they don't care about Brits. If they cared about the Brits they would require yout to get a visa, they don't. When you have done some more travelling you will get it!
If anything, the INS guy will say to himself 'why did this British tourist get a visa when he does not need one??' You are making yourself stand out with your white I94 when the rest of the plane are standing there with their green I94W. Don't stand out, don't think the INS dude will be impressed because you are a pilot, don't volunteer anything, but most importantly don't lie.
Now I bet I have really screwed you up!!! Have fun flying out here, you will have a blast!