I'm reading it as the actual support bunk came off, not a guide side wall bunk.

If that was the case, yes, you were up that creek without the paddle. I've had a fender bunk come off but never a support bunk.

There are various methods to remove a boat from a trailer on dry land, but I'd do as you suggest and just launch the boat and fix the trailer up in the parking lot. Pre-measure and cut and carpet the bunks (stainless staples) and have a good cordless drill and the necessary bolts,washers,and nuts and go at it.

We did this with Knute's (The Heathen) big pontoon.