I’m in envy mode right now so permit me some time while a drool over your tug! She’s a fine lookin’ mother-of-a-ship. There are a plethora of compact boats ranging from Sit-ins, to SOT (Sit on top) to ones with fully enclosed cockpits with watertight bulk heads. Heavier poly boats would require you to cartop them to your tug but if you plan to leave it on your boat all season long that wouldn’t be an issue. Plastic boats are durable, relatively cheap and available at most big box or sporting goods retail outlets. They can be dragged onto rocky beaches, paddled in shallow rivers and generally take much more abuse than their thermoformed or glass counterparts. Just be aware that they will degrade when exposed to UV over time if left out uncovered.
Inflatables offer versatility as they don’t require much storage space are lighter in weight, can be thrown in the trunk of your vehicle and many are framed such as one from Advanced Elements at the bow/stern so you do feel some added stiffness but nowhere near a hard-shell boat.
Naturally, much of your decision leading up to a final choice will depend on your budget. A friend of mine purchased a poly boat from Costco and it fits his needs fine but he’s more inclined to use his to float down the river without having to worry about rapid classes or rocky shorelines.
This
link might provide more insight into the materials/pros and cons and perhaps a better understanding of what type of craft might best suit your needs. I would avoid folders as they can be quite intimidating and time consuming to assemble. You might also want to rule out composite boats as they tend to be more expensive and require more care when launching/landing on rocky beaches.