I've just dismantled the rear suspension on mine for refurbishment. It isn't that difficult to drop the trailing arm, and then cut the hose (yes, I did vandalise it that badly), of course you're replacing it too so the same approach would be valid. I then cut it off the trailing arm with a slitting disk (leaving the bracket alone)
That gives you best access for removing old, using stubby spanners on a clean hose perhaps gives more chance of sorting it, just before you refit the pivot bolt.
I'm doing a Banks rear disc conversion, so I don't have the same challenges of refit, but will need to add suitable brackets to mount the long flex hose. Hope it goes well for you!