It looks like the Verge Festival at the Milwaukee Summerfest grounds will not include the Marcus Amphitheater itself. They don't need the venue per say, but I was surprised to see the layout at Summerfest for this two day event.
A quick check of the Verge Festival site, shows pictures of people hanging out near the Miller Lite stage. The picture is a mish-mosh of Summerfest fans cut and pasted to look like there are part of a massive crowd. I expect the crowds to be large for the headline acts, but if you hit Verge at 5pm, you will certainly be able to walk about and enjoy the space.
As for the "what not to bring" listing: - Backpacks and Large bags- Food- Cans, glass or plastic bottles- Alcohol- Contraband- Pets (exception: service animals)- Laser pointers- Lawn chairs- Skateboards (except credentialed competitors)- Inline skates- Coaster wagons- Kites- Frisbees- Picnic baskets- Professional Grade Video Equipment- Recording devices
This is pretty standard for any festival. You don't want to bring any of this stuff, unless you want to be turned away at the gate. Verge festival starts on Friday, June 4th, and runs until midnight June 5.