So July 4th will be fairly crowded in and near town. A few options:
There are a number of Forest service campgrounds south of estes park on highway 7. I am not sure if they are first come/first serve or if they take reservations.
There is dispersed camping in a few areas of the FS as well. Pierson Park, if its accessible due to the flood, is right out side of town and will be no problem for your cruiser. It does get some traffic but there are some nice camping spots up that direction.
Further south is Johnny Park, looks like they have it labeled as road 82E. You can actually drive that from the very small town of Meeker Park on highway 7 into Pierson park and then into Estes Park. Area tends to get crowded closer to the pavement but as you get further back there are less people. I posted up a few pictures of the drive from Pierson to Johnny here: http://www.risingsun4x4club.org/foru...ad.php?t=16149
A bit further south is an area called Bunce School road that takes you west off the pavement. There is some dispersed camping back there as well. Also a popular rock climbing spot.
Off Highway 36 a few miles East of Estes there is an area called Pole Hill. Also 4wd access. Tends to get quite crowded over the holiday weekend as its up on a hill with good views of the fireworks.
Its not uncommon to hear gunshots in either of these areas during these crowded weekends so just keep an eye out. Hard to tell what kind of judgement the person on the other end of the gun has.
Brainard lake area is not really "near" estes anymore, but could be an option: http://www.fs.usda.gov/recarea/arp/recarea/?recid=28182
Page 16 of this document has list of some of the developed FS campgrounds. http://www.fs.usda.gov/Internet/FSE_...rdb5349495.pdf
Other than that there is not a ton of stuff really close to town. Its park service on the west and north, so you are limited to south and east if you have dogs that you want to let off leash.
HTH, let me know if you have more questions or are thinking of a specific area.