The main roach hanging up is only an issue in light air, not really a problem for the mast when easing the back stay.
On my 9.1 I let the back stay right off, pull the traveler up, and then ease the sheet until the roach clears. I did add some bungy cord that pulls the back stay adjusting blocks all the way up when we ease it, that way we get the back stay as soft as possible.
That seems to be enough that we get by.
I know that a lot of 7.9s have gone to dyneema and a flicker but I am reluctant to try it.