Gaah you're right, I was mixing up SOCKS proxying with how AT&T (or was it Sprint?) was blocking some tethering apps by TTL that just bounced them through; but this is new packets so it's moot. I'm sure some kind of rate information would let them detect various protocols within SSH but I'm not too worried about that 'cause I don't use much data.
Really I just want to check my email on a device where I can actually reply to it when traveling. I have a $3/day pay-as-you-use T-Mobile contract but I've yet to try to tether with it.