I have a few swim thongs and bikinis with an uplifting panel (like a cockring) that I wear as underwear from Prevailsports & Skinz but my FireBoy bikini does the best at pulling everything up and out
I agree with Tnglvr. Fireboy (www.fireboyunderwear.com) has amazing gear. It fits so well, accentuates the bulge, and feels great on! Treat yourself :-)