Why bother? The lid probably doesn't seal gastight anyway.
Even if it does, just crack the seal in one place.
I've got 4 buckets, they are all fly-proof but none of them need airlocks.
I have lids with seals and clamps on my beer fermenters and airlocks but i have never yet seen a bubble in the airlock which is most upsetting when you want to know your beer is alive and well.
Yep, there isn't much point in trying to seal a bucket from anything but dust and flies. I even find the plastic demis are also nearly useless for being gastight, 9 times out of ten I don't see bubbles in the airlock even though there is good solid fermentation.
My French neighbours were gobsmacked when I showed them my fermentation vessels with bungs and airlocks. They use plastic barrels with loose fitting lids. I've tried the results of their methods and can't criticise them one bit. But they do have a bit of a history of doing this sort of thing!