Thanks for your kind help, everyone. I agree that the repeat structure should be the same for everyone to avoid confusion. And the problem with writing out the whole part (i. e. without repeats) is that everyone will have the same thing twice except a few players, so that’s a bit redundant.
I went with the suggestion by @Craig_F and moved the content of the second ending to the second staff:
It’s a bit unusual but I guess people can get used to it after one rehearsal.