I've launched trips off the top at ridiculously low levels. Without flying anything in.
Really, it's not a question of "Can it be done?" ('cause it can), it's a question of "Do you want to do it?"
If one foregoes a full-on kitchen, huge coolers loaded to the brim, and cases and cases of beer (and soda), one's rafts get much, much lighter. And take substantially less effort (and water) to move downstream.
In ultra low water years (and while this year might end up low, so far it's *not* shaping up to be ultra low), one can downsize the trips to self-supported paddle rafts with the trip essentially running a backpacking style menu instead of a full-on rafting style kitchen.
Doing that when the water has gotten really low has allowed us to run trips with everything from self-supported kayaks, to self-supported IKs, to self-supported 2-person paddle rafts (with one of the two people being my 70+ year old mother). We've hung up on the occasional rock, but (thus far), we haven't had to get out and hike while dragging a raft behind me.
So, barring an anomaly that puts no more snow on the mountains (we're at 80%+ for this time of year and already at 50% of the overall snowpack) and/or brings all the moisture off the mountains super early then, yes, a trip can definitely make it down from Boundary Creek in late August.
But I might be way more tolerant and experienced with low water trips than you! It's possible that your trip will make a mistake and tear the floors out of every raft in the first mile.
If you do decide not to go, cancel the permit early. There's a loophole in the environmental impact statement that stopped the reissuing of August 15 or later permits that allows them to be reissued before March something or another. Doesn't mean that the Forest Service will actually take advantage of that loophole, but they might.
Personally, I'd go...