If a guinea pig doesn't like to share a cage then it is best to house them next to another cage with a shared wall that they can interact with each other through the grids.
Yes he can live with a spayed female, whether or not you will have dominance issues depends on their individual personalties but generally there are less issues with a female/male pair (regardless of which gender is de-sexed) then a male/male pair. Another option would be to contact a rescue and see if they will allow you to take your boar and let him meet with their lone boars to see if they get along before you commit to taking one home. Age is a factor, often adults are more accepting of a young individual but a younger guinea pig can sometimes cause issues as they grow up and no longer want to be the submissive one (depending on their personality).
No matter what you do you need to be aware that he will scent mark and yes it will smell. Scent marking is a way not only to establish dominance but also to mark territory, which is why you need to introduce in an area neither pig has been before (or has been thoroughly cleaned since their last visit) and clean the cage thoroughly before putting them in together.
All of my boys scent mark every time I clean their cages, both boys in the pair will go around and scent mark all over the cage. Some boys scent marks smell worse then others but the smell doesn't linger for very long if the area is well ventilated. It also helps cut down on scent marking to leave things in the cage that still smell like them like used hideys (except when first introducing).
