OK, today I decided I wanted to figure out how to make a layback seatpost without welding, and from whatever I had on hand.
I rummaged around in my junk some while trying to work out the design.
Here's what I came up with. Took about 15 minutes to put it together.
First I mounted the seat to the seatpost with two 5/16x6 bolts.
Then I put it on the bike, and used a piece of sq tubing crossbar on the bolts, and a support post and all thread to clamp it all to the fender stay.
Got a nice mechanical look to it. I rode it hard and bumpy with my 200 lbs. today with no problems.