I have a fully inflatable raft, previously called "Seahawk II," but since rebranded as the "Mariner 3." Got it in 2012 for $115 on Amazon, $17 for motor mount, $80 for trolling motor, I use a spare battery from my basement. I've only used it once, and it worked great in protected waters. I've taken it with me many times, but didn't need to use it. It stows in a small bag, weighs 40 lb (boat only), fits easily in aft berth. Probably not very good for rowing, but it does have collapsible oars.
It is probably not a good solution for frequent use, but for occasional use it may strike the right balance of portability for a small boat. It's small enough to always have with you, available for use only if you need it.