I saw some carts down in the South 40. People would park their aircraft there, and then their friends/family would pick them up and their gear up in a cart or car to camp with them in Scholler.
North 40 is outside the gate. South 40 doesn't have the physical barrier, but there's a line where the rules change a bit.

Both are considered "outside" the show and so carts, scooters, etc are allowed.
OTOH they were cracking down on e scooters this year. Saw some in the South 40, mainly because there is nobody there to stop them, but anyone that tried to go past the UL runway was made to dismount.
That's probably where the line is, roughly... That's the area where aircraft parking used to end (where the bigger amphibs park) before the South 40 was a thing.
South and north forty are outside of the main entrances/gates - carts would be allowed there, wouldn’t they?
Yes.
So…. People can park aircraft in the South 40 and camp there as well, or can choose to just park there and camp in Scholler?
Yes. In the North 40 there's a taxiway on the north side of 9/27 beyond which camping is not allowed due to "reasons" that have something to do with the city/airport authority. Generally, in the North 40 GAC is filled from the south side near the Warbirds clockwise around the runway, and GAP is filled from the northeast corner of the airport counterclockwise around the runway until they meet. In the South 40, anything goes and GAP and GAC are all mixed up.
No golf carts or cars on the airplane camping areas with some exceptions for loading & unloading, but even that is mostly forbidden during the show.
It's not hard to get a cart or car in outside of the show days. I used to sometimes just bring my camping gear up in the car when I had a permit for the G lot and they'd always let me in (Sunday before the show). Once the show starts, no bueno.
There is a security station that marks the edge of the s40 beyond which no bikes will be allowed. Things changed a bit down there this year, so I'm not exactly sure where the line is now.
I would expect that this will continue to change as the South 40 is relatively new and a lot of things keep changing down there as they make it better. Transportation is still a very weak area...
HBC is inside, and I've seen bikes in there, but they won't let n40 people in there with them. HBC also doesn't have to go through a bag check to enter the show, so make of that what you will.... Maybe they figure it's less of an issue because it's harder to haul a bunch of bikes & beer in a homebuilt?
Beer is at least unofficially allowed. I think they know how many pilots go home with a couple of cases of Spotted Cow! If you go in most/any of the show gates, if you have a pilot certificate you can bring in beer. It's part of how Wisconsin keeps our trade surplus with the rest of the country going.

Now, I'm guessing the North 40 gate is the exception to the above, as the reason for it is to be able to take the beer to your plane, not bring it from your plane to consume on the grounds.