In our state you can partake in clubs and groups, some music programs (at the discretion of the board for the district) but not sports. However, participation in school activities requires school vaccines. Many homeschoolers are anti vaccine, so that eliminates them from that availability. There are even some things that may (again at the school and districts discretion) be borrowed from the school, such as microscopes, possible AV equiptment, ect...)
Many "special needs" children fair better at home because of the availability to work around the child's learning styles/abilities and the availability to go at their pace.
Many communities have what they call "homeschool co-ops" where certain subjects are taught together in homeschool groups, and extras are covered. We do not have anything of this nature, but I live in hickville, so.....
Just drop "HSLDA" on the table and see if they want to go up against them. Many districts do not want to go up against HSLDA and a fiscal fight over one child. Unless they have just cause, they won't push them. But I've heard many tales how a district or school will pull crap because they can because the homeschooler or tentative homeschooler do not know their rights. Fortunetly I don't think my district gives a crap as long as my paper work is complete and turned in every quarter and at the end of the year.