Do it in the water!
You're in Florida! Get the hose, cut it to length,disconnect the shaft and move it back so it's nearly out the hole in the stuffing box (maybe dive over and tie a safety line to the prop first) Dive over the side and tie a couple of plastic bags around the cutlass bearing or whatever you have where the shaft goes into the boat and around the shaft with zip ties.Get your electric pump and strong friend on the manual pump ready for action, loosen the clamps and go for it!The water will push the plastic bags into the opening. It won't be completely dry, but it will be manageable.Put new packing in the stuffing box while you're at it. Don't over tighten the stuffing box. Run the motor a few minutes with the new packing tight enough so it drips a couple of drops a second, then tighten it with the engine running so it drips once every 10 seconds or so. After a half hour or so, tighten it the way you like it.Keep some rags handy to stuff in the shaft tube while you get the stuffing box out of the old hose and into the new one. Keep the stuffing box loose so theshaft will go in easily.