I did the same thing years ago but I'm not good enough to build my own. I researched all the available boats and my criteris was exactly the same as your. Lightweight, stable and not require a trailer. I was planning to use this boat on smaller rivers and streams where no landing was available.
I narrowed my choices down to some of the Carsten models, the MoMarsh, Fiberdome products and the Hoefgen Duck boat. With the eception of the MoMarsh boats, all were double ended marsh boats that paddled well. MoMarsh did not have the DP model yet, only hte Fatboy.
Paddling was going to be my model of propulsion so so a duoble ender was going to be better. This eliminated the Fatboy. Lightweight was key as I was going to be putting it up on top of the vehicle and I was going to be dragging it over and around stuff. This eliminated the Carsten products as they were heavier on a lb/ft ratio. This lefft the Fiberdome and the Hoefgen. Both were made within 6 hours of me, both were around 65 lbs or so. I chose the Hoefgen due to the history of the boat and the builder's repuation. It was a good choice and has servved me well over the years. Hoefgen then made a kevlar version that weighed somewhere around 45 lbs and since they had been making kevler canoes for many years, I figured they knew how to make the duck boat with kelar. I never sprung for the kevlas as it was quite a bit more money.
Now that I have had the boat for a few years, I have learned much.
1. Putting the boat on top of the truck everytime sucks. It is not that the boat is heavy, the weight is awkward. At 15' long, it doesn't fit in the pick up bed all that great. On the advice of a couple on this site, I purchased a Darby Extend A Bed which should allow me to put the boat in the bed and feel OK about it.
2. Paddling sucks. I did it for years. My places to hunt were always small stream and it always seemed that were I put in was upstream of where I wanted to hunt. This made it so I had to paddle upstream after each and every hunt. I then tried to adapt an electric trollling motor for propulsion. While it worked, it was far from perfect. Tried a small outboard. Same end effect as the electric motor. Looked around for a small mud motor but each of those weighed 65 lbs or more and coat a boatload so I built my own. The lightweight mud motor I built pushed the boat over 6 mph and has done wonders for the enjoyment of the hunt.
So, what does this mean for you. I'd get/build the lightest boat you can and I would purchase it with an eye towards using a motor of some kind in the future. The Fatboy is a good choice in my opinion and I have considered trading the Hoefgen for one. As I do occassionally paddle the Hoefgen, I don't know if trading is a good option. If the extend a bed works, I've have a set up thtat will work very well for how I hunt.
Oh yeah, I've got one of those kayak carriers as well to get my boat and gear from the truck to the water. Sometimes this can be 1/2 mile or more. Without the kayak carrier, this job would suck.
Let me know if you have any questions.
Mark W