G'day Aus005,
Fitted davits to my Fisher 32 about 12 years ago and it was well worth the effort.
There is a US website Ocean Marine Systems which provided some good ideas. I assume they are still on the net.
Used a 4:1 purchase block system to pull up a 42kg hard dinghy which was adequate. Cam cleats for raising are a big help but its ultimatey best to tie off with a horn cleat. No chance of the dinghy self launching at one end that way.
I used 1'' dia s/s tube with the web support in 3/4" dia. Does not look too heavy that way.
Easy as with the Jarkan transom using the pushpit for extra bracing.
I regularly left the 2hp outboard on the dinghy when travelling. System would have a comfortable working load of at least 125kg. With the dinghy up its also a handy spot to throw all sorts of stuff in, fenders etc.
These pics are not the best illustrations but will give you an idea anyway.
I sold the Fisher mid 2013 after 15 years and its now with a happy owner in Melbourne. Now gone to the dark side with a Cummins powered Fairway 36. Happy wife.... Happy life. Still got a sailing tender though!
Cheers
John