We hosted the month of June this past year at Point Lookout, MD and it was GREAT! If we hadn't had other obligations, we would have stayed another month.
The experience was great, there are 6 or 7 camp hosts there, so you have help with what you need to do.
Jonas Williams is the ranger you need to speak with if you call the park.
They are always looking for more camp hosts and it is close to your home. It is about 60 miles south of Annapolis.
The duties there were to just be available if there are any questions from the campers. They expect you to be there at the very least on Thursday, Friday, Saturday and Sunday mornings. You are asked (not required, but requested) to assist for one hour on Saturday and Sunday evenings 7-8 pm, in cleaning up the picnic/beach area. (If 2 of you go, that's 4 hours) On Sunday, after the campers have left, the hosts rake the sites and clean out the firepits. Quick and easy work.
I also volunteered as a greeter at the nature center, which was fun since my children wanted to be there anyway.
We also host at a Virginia SP for a couple of months each year. In VA, we are required to be there with 2 days off each week. We sell firewood and ice when the camp store is closed. We help out in the store, relieve the contact station workers and other things that are needed within the park. It's pretty non-strenuous and we are always told that if we are not comfortable doing something, just say no. We are also told that we are NOT to take any actions with campers, just notify the ranger.