Max capacity stress

I wouldn’t stress about it too much. You will have some that decline which will give you more room. And if 170 is the max, I am sure they’re used to making it work in the best way possible.

If 170 is the max then I'm sure the venue has ensured that 170 can move comfortably in the space. I wouldn't stress about it too much, they've probably made it work before! Also you'll likely have some decline!

You’re going to have declines and likely even people who RSVP yes and don’t show up. I wouldn’t worry about it.

As others said, you are likely to have declines, especially if you invite many out of town guests. For example, we invited about 150 to our wedding (pre-covid) and ended up with 115 guests total. Also, the max capacity usually still ensures that guests can move around comfortably.

It's true that some people will probably decline. But the common advice is never invite more than your venue can hold -- 100% attendance does happen! You will also need some space for your vendors because some of them will be eating the meal. So definitely don't invite any more.

Does that count include vendors that will be there during the reception? I wonder if their max is seated guests or total people in the room for safety code. I'm thinking about photographer, coordinator, DJ/musicians, staffers, officiant etc. My venue has 250 max capacity for people, so we needed to consider vendors that that will be in the room, as well as getting a meal.
The easiest way I could think to do this is to list them with my guests in my rsvp tracking. That way they're always in the count.