I used to be in the Army many years ago and wanted to transfer to the Army Air Corps. They wouldn't accept me as the Ishihara test showed a red/green deficiency.
A year or two later I resigned and did my PPL. I told the AME about the problem and he sent me for a Giles Archer Lantern Test and also for a different test (can't remember the name but it involved matching blocks of colour like a paint chart).
The conclusion was that the problem was bu@@er all to do with my colour vision, simply a difficulty in seeing the pattern in the Ishihara test. I was told I could have a Class 1 if I wanted. That was in 1974 and I've had no issues on that subject since.
Hope this helps, give the lantern test a go, nothing to lose except the cost of doing it.
Mike