I would take a strong look at the northern end of the trail, from the Aucila River down to Cedar Key. I think that would be a gentler introduction to overnight camping with a kayak. You might even consider the Apalachicola or the Suwanee river to get used to the rhythm of camping with a kayak. Being a former backpacker it will be pretty easy for you, now you get to float your gear instead of carrying it. Lots of good advice above that I agree with, so I will not go over that stuff. Good Luck!