Shots of the rig are below, I'd forgotten that the lens mounts upside down on the Lens2Scope for some reason - if you have a lens with a tripod collar, the collar must therefore revolve to 180 degrees to have the eyepiece vertical.
As this is intended as a travel setup with shorter lenses, I've shown those with the travel tripod I'll be travelling with - hama Traveller Mini Pro and the head supplied with it, which is very light (700g), rises to about 4 feet but isn't that sturdy (OK for a spotting scope, probably not shooting with a K-1). The 400 & 500mm lenses would overload the tripod foot and probably ball head - I've shown those on my Manfrotto 190Go, an old (but light) Uni-Loc 30 ball head. Aligning the longer lenses at 40x & 50x is not straight forward.
Pentax-M 75-150/4 (7.5x-15x):
Pentax-M 200/4 (20x):
Sigma KA 400/5.6 APO (40x):
Tamron SP 500/8 55B (50x):
Tamron SP 500/8 55B with an earlier 'straight through' monocular converter (50x):

---------- Post added 03-16-19 at 01:42 PM ----------
Originally posted by Thagomizer
Just a thought on using longer or heavier lenses. Would you be able to mount the tripod foot into a longer plate for better balance on a tripod?
You could probably mount it on something like an Arca-Swiss rail and slide it forwards/backwards, but the foot is only plastic and slides/clips onto the converter - too heavy a lens would break it or make it hard to lock it in position.
I don't have a lens between 200 & 400mm with a tripod collar, I think something like my Sigma 70-300 APO would be too heavy.
Last edited by johnha; 03-16-2019 at 06:54 AM.
Reason: Added the magnification powers for clarity.