Abe,
I used a 10′ piece of aluminum tubing from either Home Depot or Lowe’s….can’t remember which. I believe it’s one-inch in diameter. It was very reasonably priced….but can’t remember exactly what I paid for it. Dang I’m getting old.
You can get a PVC “Tee” and some caps. Cap one end and epoxy the Tee to the other end with caps.
Here’s a photo of mine…..probably $40 bucks tops for the setup.

I did a similar trip two years ago. Camped at Flamingo a few days and kayaked the Glades and the bay. Then went over to the Marathon area and fished the flats from the kayak. We would kayak out to the flats….stake out the kayak and wade to the edge of the creek channels. We camped at Fiesta Key campground….mm70.