Previous flyer jobs were a lot easier... lil openings.
The pictured gap under the roof is about big enough to put yer fingers into and 5 FEET LONG.
There is another gap at the end of the roof around the corner bout a ft long x 3/4".
Lady says theres a party every night in the wall nearby.
Should I close up MOST of the 5 ft gap and use an AES trap/colony type AND close MOST of the 12" gap and do the same?
I do not see any dirt, like where it rubs off when critters go in, anywhere, so don't know exactly where to set traps, since there is no sign/droppings.
I cannot get into the crawlspace behind gap,it is closed off from the attic...since it is an added on room.

I dont think the gaps you are showing and talking about are your primary squirrel entry points.I think you need to look harder to find a more probable entry point. If it even is squirrels. It may be bats or mice with that small of an entry if that is all you find. Flyers need a little bigger opening around a golf ball configuration either already in the structure or one they have chewed large enough for their entry.

If you cant find anything I might suggest putting up a couple of trail cams pointing at the suspected parts of the home for a nite or two.

Sometimes flyer entries can be challenging to find them. I once had a job that really had me stumped for a few days until I started looking things over very closely again and found some mortar joints missing above your sight line from the ground up on the exterior stone chimney face about 10 ft from the ground. Once I found it I was good. Put up a one way door and came back a week later and they were gone.

Traperjohn, I see alot of jobs like this all are metal roofs tho and I see your right next door in NC. The party going on discription is common with flyers. I would do a complete inspection for other openings. Do all your exclusion and yes put up a colony with 2 minimum baited traps at the colony.

You're on the right track. Treat it like a bat exclusion, seal everything but the entrance/exit which you positive set.

At least in my part of the country Flyers seldom ever leave any sign of their passing through their entry hole. We see that kind of construction gap all the time and it is a favorite entry point. I just excluded a house that had over 300 feet of such gap. As warrior said...treat it exactly like bats only set multicatch traps over one or two holes rather than checkvalves.