I don't see any advantage in 4-5" shields. All you will do is spend more money, give up clearance, add noise, and slow the arrow down more. If 3 of those feathers don't fly there is something seriously wrong, and you would be better off tuning more or working on form.
I shoot 4-4" parabolic AMG feathers. The AMG are a little lower profile than some. I don’t think the 4 AMG’s give much more feather area, and stabilization than 3-4” Trueflight. The AMG are also a lower cost option. It is probably cheaper or real close to the same for me to shoot 4-4” AMG than your 3-5” shields. I like that I don't care what way my arrow goes on the string and with the 75/105 my bitz does and set with the 105 horizontal, I get great feather clearance.