I have the same exact tub for my adult male, and I know what you mean about it being easy to lift up on the sides!
I went to home depot and got these little silver and green clamps for about .40 cents each and clamped the lid to the tub in the middle of the sides.
They look like the clamps you attach to your battery to jump start your car but really tiny. Can't be more than an inch long. So far they've worked perfectly and he hasn't escaped!
I will have to agree that I offer my BPs food while in shed, some will take it some won't. No big deal if they don't. I am however very careful to watch them, because I'm afraid they're more likely to get bit during this time. I figure with their eyes being cloudy they probably can't see the rodent as well and with the high likelyhood of them being disinterested... It just seems dangerous to me... So if you drop a live food item into the tank and let it run around, I would keep an extra sharp eye on it during a shed. If you hold the food with hemostats or if it's frozen/thawed then there should be nothing at all to worry about.
Good luck!
Awesome, thanks. I'll pick some of those up tomorrow! He eats f/t, so no worries, I'll definitely offer him the prey in five days though and see what happens.