If you have shooting rights over land that's also got stock fences then you should get permission to build stiles wherever you might need to cross. The farmer only has to provide crossing points on public footpaths etc.
I farm quite a bit of land that I don't have the shooting rights over, but if I see anyone getting over fences where there's no crossing points then I'll tell them to clear out, even if they do own the sporting rights. At the end of the day it's my land and my fence, and the whole concept of someone else owning certain rights over my land is a little outdated in this day and age, so they need to behave themselves or I could really put a spanner in the works of their shoot! As it is, provided that we all look after and tolerate each other's interests then we get along fine.