Summer: how to avoid visibly sweaty butt crack?

So now the weather's getting warmer, I want to get ahead of a major problem that lots of people must suffer from: nasty ass sweat showing through the seat of your pants.

I wear boxer briefs and jeans / chinos / chino shorts. Normally it's fine, except as soon as I get on the bicycle in the summer heat, the seat pushes the butt crack sweat right through my pants and I end up walking around for the rest of the day looking like I've got mild- to moderate- anal leakage.

The only surefire solution I've found is wearing dark coloured basketball shorts, which breathe super well and wick and dry the sweat instantly. However basketball shorts aren't ideal because they're so casual, and also the pockets are no good for carrying phone / wallet etc.

I've tried wearing a pair of briefs under boxer briefs which works temporarily as an extra layer, but ends up super stanky and is not very comfortable.

I saw some expensive boxers that had an extra waterproof layer to stop ass sweat ("Ejis" brand) - has anyone tried those, or is there a cheaper alternative? I've even heard of people lining the ass of their underpants with sanitary pads?

Surely someone must have solved this problem?