Judging by the condition of the lower welds on the rails, overall the frame is in the decent shape. BUT! Given the fact that whatever paint the prev.owner used is flaking off, I'd be really caution and, if possible, poked around with a screwdriver; it's very likely the surface/rust wasn't treated properly before painting, and was rather 'encapsulated'. When done incorrectly, it rapidly accelerates the decay. Pay attention to the inside of rails - some holes are big enough to stick your finger in and feel inside (ugh, sounds a bit wrong). Also, check the front and especially the rear crossmember behind the bumper.
In any case, even if frame is solid, treat it again this summer. And do it right this time.
You were spot on man, thank you. Unfortunately upon farther inspection on the lift at a Toyota dealer, we found major issues with inside of the frame
It's such a shame since the rest of the car checked out well and had a clean record.