Thoughts please!! Is this reasonable? How to address issues moving forward?

My son is coming up on 16 months.

To this point our current custody agreement is

Week 1:

Tues thurs 515p-7p

Week 2:

Tues thurs 515p-7p

Sat 9a-sun7p

Overnights just started in December.

His dad has had a history of alcoholism, as far as I can tell things aren’t AS bad but it’s usually the evenings that he gets trashed so I wouldn’t see it. There have been a few times I’ve suspected he was drunk or known he was hungover. He and his fiancé have large liquor bottles in their kitchen window that are regularly rotated, and he told the mediator he drinks a few times a week and gets drunk once a week, which I know is likely downplayed from reality.

My son has come back most often clean, well fed, happy, etc. (a handful of times in a WAY overfill diaper or dried poop, or absolutely filthy from playing in the dirt) I know his fiancé does the vast majority of his care, his dad changed his diaper ONCE and I knew because he didn’t even fasten the diaper just literally slapped it on.

Anyhow, he’s suggesting adding Friday to his weekend and removing the Thursday that week so

Week 1:

Tues thurs 515-7

Week 2:

Tues 515-7

Fri 6p-sun 7p

I’m wary of this because of the drinking and consecutive nights might be hard on our son he also has yet to do the court ordered parenting class and keeps avoiding showing me he has done it. He also said that 2-2-3 is what we “should” be doing for his age and that he can do 5 days away from me, according to whatever source he is going off of but won’t share the source.

I feel like this is reasonable as the courts most advanced example has 2 non consecutive overnights / week, so every other week would be much more feasible. Would it be best to agree to this provided he proves he has done the class and I address the drinking? If so how should I address the drinking? Or should we keep doing the original for a little longer? We are in a really good place right now so as long as I can approach it in a respectful manner it shouldn’t be a huge deal.