I am okay with number 1 but I feel like if I give an inch he takes a mile
Then why don't you go with #2 for a while? Phrased more diplomatically, of course. And then, over time, as all three of you get settled in, you can shift as you need it. Maybe if things are working out well and H is following the plan, you could be the one to suggest that H/MIL take a Wednesday afternoon occasionally. But not the other way around.
Our parenting plan is going to say next to nothing, because we work it out on an ad hoc basis. But you are not in that position, you need something more spelled out right now. And that's OK, enforce what you have for a while, and let things take their course as S gets older and as you and H settle into co-parenting.
Do you get along with MIL? Maybe you could invite her to join you on an outing that's clearly your time? Just to make her feel included?
