I checked the underside of the tub this morning, and the foam has solidified. I was a little concerned about this, as the foam came out of the tube last night was oddly very liquidish. I think forcing it through the tube changed the composition and the normal immediate exposure to air. I think it took a bit longer than normal to solidify, and I don't think it rose as much as I would normally expect it to.
But the real test is the squish test.
Looks like I'll be doing a part three through the drywall in the hallway. At least this time I don't think I'll need the long tube apparatus. It only seems to squeak towards the drain and I'm guessing I just didn't give the foam enough time to build up under that area. I said before, it came out very very slowly and I was working blind.
But it's a good start, and much much better than it was before.
Off to Home Depot!!!!