Marissa, Lois Ann and Humboldt, I believe, all have Web calendars you can look at to see if they’re even running trips during the week, and you can e-mail or call to find out more. Lowest number I have seen for a trip is 6.
You’re bringing drysuits, yes? A must if you think you’re going to do a three-tank trip.
Are you brining tanks? Last time I checked no one rents anything other than Al 80s in S.D. I always bring my 100s, especially on the Yukon where you can hit 105’.
Oh and I can also definitely second the non-recommendation for LJ OEX. The people working there are useless, but they’ll be happy to try to sell you gear they know nothing about. I once had to rent a tank there, it was $12. A couple of months ago I stopped in for a fill, they charged me $8. Apparently the compressor had been down and they were trying to recoup losses, at least that was the story. Who counts on making money off air?