AMAB and masc presenting.

I've gotten really into formal wear lately and am experimenting with how-far-is-too-far when tailoring one's slacks especially close. I'm loving the fit of my slacks where I have them now but I can notice the line of my cotton boxer-briefs even when they aren't bunched up. The loose cotton also has a tendency to roll/bunch when I put my leg down a pant so I'm definitely looking to buy a different solution soon, wondering which options might be best though.