Try using garden shears, they can cut a few plants at once. It IS slow work but at least the results will last a few years. You really have to triage - only cut what you really have to at first so the trail is followable. I've cut a million rhododendrons with loppers - they never go away!!!!!
Good luck with the large crew, although you do know a few Gorge hikers...for me, a large crew is a couple surprised friends (trail work?!?!)
I have been enjoying the Portland Hikers site, very fun and informative. I would like to join you guys for some of that Gorge abandoned trail exploring, but probably not until September or so (it's going to be a busy summer, lonnnnng story)....