I tend to run my .204 at the upper window, and I F/L size the cases every other firing to prevent problems in the field.
Since replacing my barrel, I'm considering just getting a F/L die blank, and ream it to match the new chamber. I have a few rifles that have had custom dies machined, and the resizing even F/L, is so minimal that the brass is not overworked, nor is accuracy hindered in any way.
Most people believe that benchrest shooters only neck size. However, most do not, at least the ones I'm around. Most run their rifles up around 70,000 psi in say a 6PPC. This requires F/L sizing, but is done with a die that matches the chamber, thus no ill effects to the brass.
In your instance, it sounds like you may also need to shorten the interval between your F/L and neck only sizing. If you are just shooting varmints and rodents, they won't be able to tell the difference.
Mike