To me, the closer you can make it to a Cobra-style trailer the better.
But there are still a few Minden Fab trailers in use. The ones with built-in rigging aids (wing root dollies clamp the wing root and pivot in two axes) are very good.
Minden Fab trailers seemed popular for SZD42 (20m Jantar 2A / 2B). Owners can solo rig.
This would be an easier trailer to build and still provide ease of use.
Jim