I would try maybe 6 weeks - you should be able to get significant progress in that time frame. You can always return to it later.
You can try a max fs at the end of it; if your back is really limiting you and you get it considerably stronger, you may make a PR. But it won't be a strength program in the purest sense, so you may not see a PR, but what you're trying to do is shore up a weakness that's holding you back. After you make progress with that, you can push the overall strength more.