Getting him drunk and passed out just to sniff his underwear is sneaky and underhanded. If he finds out, that's the end of the friendship.
But just hanging out naked together in a hotel room, or even jacking off together, is not going to break up a friendship. On the contrary in many cases it can make the friendship closer and stronger. It's a bonding thing.
If it's all above board and open, and you are just having some "boys will be boys" fun together, then everything is fine and you can still continue with a great friendship.
But if it's all sneaky and done behind his back, that is no way to grow a friendship and could end up destroying the friendship if he finds out you did that.
By the way, you state that you and him are "literally best friends." How can it be that your best friend doesn't know you are gay or bi? How can that be a real friendship if he doesn't even know that fundamental fact about you?
The things that break up a friendship are lying, cheating, stealing, using and dishonesty. Simply jacking off or getting dressed/undressed in front of the other guy does not break up a friendship.
Any straight guy who would be so offended by the sight of his friend naked or the sight of his friend jacking off in a hotel room has too many hangups. Among my straight friends, I think 50% of them if in that situation would just say, "no thanks" and laugh it off. The other 50% would be tempted to jack off themselves and would even do it if they happened to be horny. But ending a friendship over that? That's only for homophobes or extremely insecure men.
I have one straight friend (actually I think he's 10% gay) who is homophobic and recently I asked him by email to take some pictures of himself naked and send them to me by email. He refused, saying he did not want any pictures of him "sent through the mail." But it certainly didn't end the friendship, in fact his next email a few days later, on another topic, was just as friendly as always.
Oh well, it's your friendship to do whatever you want with it...