Personally 220F is where I get concerned. I'm not concerned about 220 assuming it is for limited time, but I wouldn't want to be at 240 or 250 for extended periods of time.

It's worth mentioning that transmission fluid manufacturers are comfortable up to 280 degrees, and so is Toyota as I don't think the transmission temp idiot light comes on until about 300 F

When off-roading if you're in 4hi I'd try dropping into 4lo. On occasion when sand is really soft here my temps will start to creep up in 4hi but I drop into 4lo and they drop right back down. I've never had high trans temps on trails in 4lo, even in stop and go crowded trail conditions in summer.