All the two-point mounting solutions are nice as they prevent any potential differential flexure.
My brick-and-mortar camera shop hooked me up with this Manfrotto 293 Telephoto Len support
which is a plate with a riser quick-release mount for the camera at one end, and a half-collar and strap for the other end (Length of entire plate adjustable).
Plate has 1/4 and 3/8 holes in the bottom of the plate across to mount to a dovetail given the balance point.
I use a plastic wiretie to snug it in on the collar rest.
$67 at bhphotovideo for example.
Can handle many types of large lenses.
disadvantage is due to the camera mount, you cannot rotate camera to frame the shot on a EQ mount.
per request I have included a photo of the bottom.
The quick release plate to attach to the camera (sold separately-the usual one for Manfrotto heads) comes with a 1/4 to 3/8 adapter so the bigger holes can be used as a smaller 1/4 as well!
Edited by t_image, 14 August 2016 - 05:21 PM.