I know exactly what you are talking about. I used to take my mom's '68 Cutlas wagon on fs roads and back into the woods to the moto cross tracks when I was 15 yrs old. The only problem I really had was that the headlights would pop out after you got the car airborne.
And I'm not knocking you at all, and I certainly don't want to be the ww boating Nazi. You're not letting the fact that you don't have access to a ww boat stop from paddleing; your making the most out of what's available and your researching better alternatives. Half the reason I chuckle is because of thinking back to the stuff I started with. Your learning to read the water. You're living life, enjoying good times with good freinds and family, and having a blast doing it. Totally my kind a guy,dude, no doubt.
I'm not thinking about danger in a class three, rather the fact that a rec boat such as the Otter can certainly retard your growth as a ww paddler. You won't help but to pick up some bad habits and bad stroke technique etc etc. Paddling is all about the symbiotic relationship between body, boat, and blade. A rec boat does not allow you to athletically use your lower body; it relegates you to almost dead weight status in the boat. But seriously, whatever, it is what it is.
Not to mention you could be rolling and bracing by now.
Its a humonguosly wide boat that really won't allow access to a decent vertical power stroke.
There are no rails to speak of; it's ...LOL...I'm just picturing the shape of the bow and stearn... and the flat, (yet not planeing, hull), and the cockpit that fits like a...o Jeebus.
Oh well, I mean of course you gotta admit it's a frikin chuckle that you're on class III in an Otter, thats all. If you don't chuckle about it now, then you certainly will this time next year.:ylsmoke: