The issue with the rear arms is that the nut will probably come off, but the long bolt will be seized against the arms.
Before you do the job, soak that bolt and hub in lots and lots of penetrating oil for a day or two beforehand.
What I recommend is heating up the hub where the bolt goes through, and applying liberal amounts of penetrating oil (PB blaster or liquid wrench). Give it a couple hammer whacks every now and then. Do this several times, and give the bolt a shot with a hammer, it may move, it may not. The bigger the hammer the better. Air hammer may help.
Hammer, heat, spray, hammer, heat, spray, hammer heat spray. The bolt may turn too - if you can get it to turn it means you're getting close. Just keep working it.