On the level...should be doable for one person.

Good to hear that a single person should be able to use a
manual-powered trailer dolly to move a boat.

My driveway slopes to the back, so not only is it hard to get the
boat started (especially if it's been sitting for a while), but you could
lose control backing it down. If you are reasonably strong, I'd try
the manual model at a fraction of the price.

Actually the area where I want to park the boat is also slightly
slopping down (just a little bit). I will make sure I put the
wheel-stop-block in the intended location ahead of time -- just in
case.

I am wondering if there is a device to trigger the brake in the trailer
without having the towing vehicle attached to the trailer. Then I can
hit the "brake" button on that device in case the trailer started
gaining momentum and I cannot stop it (and I put the wheel-stop-block
in the wrong place). Any idea?

Jay Chan