I secure my tubs with the big giant office clips. It is not recommended to use weights because the snake can still try to push up the lid a little, tires out and the weight can crush (?) its snout or head, or so I heard on reddit. Another way is to use velcro on the lid to the tub. I did that originally and lets just say, it works too well so I would not recommend that either. Some people uses those luggage straps alone or in combination with clips. I have not tried because I find it more annoying than the clips. So clips works best with the tubs that latches on the sides or one of those waterproof tubs that have locking latches on all sides of the tubs (This is the more expensive option and most liked by those who used them). I use about 10 big clips on a 41 at tub for my bp.
I would not recommend any of this for any snake with a skinny head, like a colubrid or smaller snakes. My Children Python started out in a tub, locked and clipped all around, and it still somehow managed to escape TWICE without so much of a scratch.
If none of the above appeals to you, go rack.