I'll probably end up referencing this book ad nauseum because I like it so much, but I am reading a book called "Masterminds and Wingmen," which is about adolescent boys.
The boys interviewed for the book said that far and away the biggest punishment is to cut them off from their friends AND the means to communicate with them. Grounding at home doesn't do anything if they can still use XBox live, their phone, Skype, etc.
What you are proposing isn't punishment, and isn't related to the "crime." Furthermore, what a boy needs at this age is MORE time with family, away from TV and computers and phones and friends, not less. What's he going to do at his mother's house? Probably play video games and text all weekend. Not a punishment at all.
I would suggest that you come up with a consistent plan for how he earns what he values, with is time with and communication with his friends. If he can't get his schoolwork done, then he clearly shouldn't have the leisure time to chill out and hang with friends. What does this look like? For starters, limit media during the week - take the video game controllers on Sunday night, and give him his phone only for an hour or two in the evening, after he has shown that his homework is done, he has studied for tests and has completed work on long-term projects. Set your wi-fi so that he doesn't know the password or can only access it at specific times.
Then on Friday, if all of his work is complete, he can have the game controllers back and make plans with his friends for the weekend. Outstanding work? No privileges until it's done. And when this gets chronic for us, there is no grace period - missing work means no socializing that weekend, even after he catches up.
It's exhausting and requires that you, your husband and his mom get on the same page as much as you can and keep each other in the loop, but if you crack down on this now, it may nip it in the bud. The son for whom I need to do this has ADHD and learning disabilities so that makes it harder for him to establish these good work habits so this has been dragging on intermittently for years here, but it's the only thing that works.
Don't leave him out of the trip.