DS (nearly 3) has been out of nappies for a week or so. Right from the first day, he has had an almost perfect record when bare-bottomed, and complete failure when wearing anything at all on his bum. He always says he doesn't want to go when asked and really fights being put on the potty, but is great at taking himself off when necessary (as long as he's naked). We've had a good few days at home, but are now embarking on a busy week (school run and lots of activities for older DD, so can't put them off). He pee'd himself 3 times before the school bus. I was quite tempted to take him half-naked on the bus, but I'm not sure this is very socially acceptable!
Any suggestions about how we can convert his bare-bottomed-brilliance into success when dressed?