As you have already learned, go south 87 (exit 31 on I-10) and you will come to a road - Range Road 213. This road is on the west side of the Egli property, but I am sure that you do not need a permit to use this road to access Grassy Point. However, call this phone number 850-882-4165 (Natural Resources Office - Jackson Guard
This is the information number and Jackson Guard is where you go to get a permit. Just one thing to remember, do not go off of this road going in or you may wind up in a restricted area, although they are good with signage. Good luck.
I hunt Eglin just on the other side of 87. Beware of snakes and bears.