Our life is different because C lives with us.
But most often time I have with C is spent catching up on chores and talking/hanging out while we do them together and almost ALWAYS we have at least one of the kids-but quite often we actually have our kids and more!
I think it's important for Mono to understand since he doesn't live there that there are things that need done over the weekend and things that you want to do as well. Maybe you could get the kiddo to help you two sort the laundry and run it to the appropriate rooms (my 9 year old does this with me a lot). I'll start making folded piles and he'll run mom and dad's to our room put it on the dresser (I will put it in drawers before bed talking to Maca) and take sissy's to her room and put it on her dresser, take C's to his room and set on bed etc.
If you toss a load in the washer before you start it darn well may be done before you get those put in the right rooms, flip it over, put a new one in and set the oven timer for 1 hour. Then do the couches. By the time they are done the timer will be going off and you can flip the laundry. That's load three into the wash. If the boys (mono and kiddo) dush while you do the couch OR they could do the couch together and you could dust you'll basically be done at that point with that list.
Also-if Mono doesn't mind it's good for the kiddo to see that he too does "work". Something we learned with our older kids (18, 13) is that they really didn't get that Maca actually DOES WORK when he leaves for work. They knew he left and money came in because of it. But they resented doing chores-because he didn't and they actually SAID "dad doesn't have to". Because all the work he did was out of sight, it was non-existant in their little minds. I think that's one reason boyscouts and girlscouts do things that get the kids going in to people's jobs to see what the "work" is that they do.
So if Mono sets an example of doing little chores it will help the little guy see that everyone has to do their share.... Even though Mono doesn't live there-it's a great opportunity for him to set an example for a child he greatly cares about. That is something our family has always done. When guests come over they help make dinner, they help clean up the dinner mess etc. (we often will have in excess of 20 people over on holidays including kids).
Instead of thinking of him as a "guest" to entertain, think of him as someone who is joining your family. As a family member even if he doesn't LIVE their he is a helper....
"Love As Thou Wilt"