Just do it. Once you get used to it you will not go back to wearing underwear.
Briefs make me hot, sweaty, itchy and smelly. Boxer-briefs are not much different in that regard. Boxers bunch up and get uncomfortable. Freeballing is way more comfortable than any other option. My goods always feel cool and fresh, no need for deodorants nor jock-itch powders and creams, no white stains on dark pants from deodorants rubbing off when I take a pee.
Erections will happen but most people will not even notice. Think about how often you look at crotches. You will find that you will only look when you are in the mood to see bulge, swing or whatever. At other times you look at faces.
I once walked along the beach with my wife and asked her at the end how many guys she had seen who were hanging free. I asked her because she was always telling me that my free-hanging cock was visible to everyone so I should wear underwear. She had not noticed any but I had counted over 20. That showed her that others do not notice my cock swinging like she does. Only those who want to see it are likely to. I say, let them see it if they want to.
I have not worn underwear for more than 2 decades. My wife accepted it long ago. I never try to hide it, all of my family and most of my friends know it. It is just a part of the character that is me.