Ok my man. First off ditch the swimsuits that have any elastic, number 1 way of showing you're a tourist and now the Life Guard has his eyes on you.
2) who in the hell wears swimsuits which we will now call Trunks!
3) no Trunks shall have any liners or anything under them! Boxers , grape smugglers, mesh.. all things to rub your nuts and head.
4) get a real pair of Trunks, personally any O'Neil hydro Trunks are good.
I went for over a week wearing the same Trunks in 86° water with no Rash anywhere while surfing in the Maldives. Yes I have a penis.