Between these two options, which is more important to you?
1- Maintaining the bestfriend relationship
or
2- Trying to label his sexuality without asking him personally
Here's what I think you should do. Focus on yourself and find out who you are. If you are now discovering your sexuality at the age of 23, you have soo much more to learn about yourself. I don't think you stated if you came to terms with your sexuality and have come out to anyone. That's where the real journey begins. Just don't be surprised to lose any friends or fam. Just know, you are perfect the way you are and if people can't accept that, then you really don't need them in your life.
I do understand your situation though. You're just curious, perhaps a little lustful but it no way do I think you want him romatically. I could be wrong. You're most likely just turned on by your friend and that's totally fine. We've all been there. We still experience this no matter how old we become. This would turn most guys on if a "straight" buddy were to do the things he asked you haha. Pretty sure 95% of us would fool around with him in your situation.
Why try and find a label for your friend when he could just be that comfortable with you because of your friendship together. As you can see, being soo focused on the matter sort of threw a wrench into the whole machine. If you are adament on getting the answer, you will most likely ruin your friendship forever. Even if he tells you "straight" would you believe him or still question him? Would you try and seek answers because it wasn't what you wanted to hear? This is a dangerous road.
To me, he's the type of guy that falls in love with women, wants a future with a wife and until that happens, he doesn't care what he does as long as he has his fun. He's young, comfortable in his own skin and just couldn't care less if he got pleasured by a guy just because it just feels good and plus he's lonely/horny. He's made it clear that he's explored his body and knows what he likes. Associating a guy playing with his hole doesn't make him gay in any way. He's vocal with women that that's what he likes and kudos to him for being able to communicate that to a partner. Just because he's been requesting a lot of gay activities lol, shouldn't label him as gay. Let people be curious and have their fun while not being judged. I believe that pure physical encounters can exist without it leading to emotional/romantical feelings.
This is what I would do in your situation. Invite him over. Give him a sincere apology over the camping trip and explain that isn't how I truly felt. I would tell him that I never fantasized about him in that way and to recall what I did that night, disgusted me. I would ensure him that I wasn't in love with him but I can't help being turned on by him when he just flaunts a nice body and package in front of me so really, it's his fault lol. Tell him that I've come to terms with my sexuality as I learned a lot about myself recently. I would say that our friendship means the world to me and would never want to jeopardize it. Now knowing that our friendship means the most to me, I still want us to be best buds but the new me likes dick so you have to accept that side of me for us to work. If he can't accept the truth then it's better in the long run. All you can really do is just be yourself and be honest with him.
Don't bring up anything he has done as far as the pics, nakedness, ect. Leave the ball in his court and if wants to bring it up then you guys can talk about it. Let him come to you first or if he requests another hj/bj from you, bring it up but could ruin the moment so remember to ask AFTER swallowing his babies lol. In my opinion, you shouldn't fool around. You're too new to it all. If you are messing around with him and catch feelings, that's when everything will just blow up in your face and you lose it all. You could be a jealous person if he suddenly stops messing around if he finds a woman. You could think you did something wrong if he stops being sexual. There's just a lot that could go wrong and believe me, it's not mentally healthy and could wreck you for awhile. Only experienced guys that can draw the line with their feelings should ever risk their relationship with their best friend.
Anyways, I always type soo much so enjoy the read haha.