To piggy back on what Tom just explained, keep in mind my experience was with the SVRA in 2104.
We rented a F1 garage as I stated previously. I don't recall the garage number, but it was a handful up from garage #1. #1 garage is just past the area of pit out for the Indy oval. We were up from that, straight across from the entrance into Gasoline Alley garages at that particular end.
The F1 garages are large enough to accommodate 3-4 cars depending on what cars. We had a Trans Am Jag and three Prod cars set up and still had plenty of room. However, the F1 garages provide no air hook up, no running water except for a small hand sink and limited electric. The garage is plumbed and wired for European stuff. The tv brackets and coax still hang, albeit empty, from the ceilings. Front door and back door to the garages. Front doo faces out to Gasoline Alley area, back door faces Indy oval pit road. Good breeze if it gets warm. Can be noisy though with cars blasting past just outside the door on the front straight.
The Gasoline Alley garages, while considerably smaller, did have electric and air. Not sure if those would be available for rental at the Run-offs.
Traffic is one way through the paddock. You will line up for false grid in Gasoline alley and enter between the oval pit road grandstands gap, make a hard right down pit road to enter the track at what is oval pit entrance.
We were required to park our hauler in the large area behind Gasoline Alley. It is a hike bag to the garages. Others paddocked down the infield area behind the front straight grandstands. Plenty of space, SVRA had 750 cars. Some grass, some asphalt.
We ran the configuration whereby you enter the front straight at oval pit out more or less and blast down to T1. The twisty bits prior to that are slower in a big car like our Jag.
The folks at Indy are friendly and very helpful. Just obey the rules and traffic patterns they establish.
For SVRA, VP Fuels was setup all the way down by oval T4 at the end of the grandstands. Have a golf cart, four wheeler, pit tugger etc to carry your fuels jugs back...it's a long walk.
Overall the experience was great. Just have you logistics planned out in advance. No different than any other large scale event. And as Tom expressed, remember you are their guest.