After reading where you are hunting and what you are dealing with, if you really wish to run a long-tail, you need to invest in a 14-16' flat bottom jon boat, and a wide one at that. I would go with the lightest 16x48 you can find.
You will not go very fast, hull speed at best because it will not plane off, but it will go through any water & weeds just deep enough to float the boat.
Also, a 9.9hp longtail will be fine in weeds, but if you intend to push the hull through mud, you will be disappointed, just not enough torque. Make sure to bring push poles.