Phoenix,
Let me admit, up front, I have very little constructive information to offer. Of course, that has seldom stopped me before.
My personal experience on that portage dates back over 25 years. At the time it seemed merely "longish" but not particularly foreboding... unless you find severe "tick infestation" to be foreboding. By the time I finished double-portaging it, I picked off 17 of the little beggars. It was an early June trip, as I recall. Hot, sweaty, tough but I would say "do-able" - at least back then - for older campers.
Since that time, a number of friends have either tackled or attempted to tackle that portage. Apparently blowdowns really screwed up the works several years back. One of the most experienced trippers and bushwhackers I know actually "gave up" trying to get through the mess one year and re-routed his trip. A few years later, a couple other experienced paddler friends reported the portage itself had been re-routed and was considerably "more challenging" than in the old days. Frankly, I haven't heard anything recently EXCEPT I recall seeing a portage crew report from (maybe) two years ago indicating that park officials had been through there.
Given the reports I've read AND the accounts provided over the campfire by friends, I guess I'd
strongly recommend calling the park office in advance for any updates they might provide. That area of the park is worth visiting, if possible without taking major risks. It's excellent for wildlife sighting possibilities (spotted the largest buck I've ever seen), it offers good fishing (including largemouth bass on Yeh), and better-than-average solitude.
I will be very interested to see what replies you receive on this thread. Also, if you DO check with park officials, please let us know what you hear.
Good luck with researching conditions on this portage!
Jimbo
P.S. Be sure to lather yourself in DEET if you head through there in May or June!