You raise an interesting point 
. With such a wide range of mounting arrangements used on different sites the antenna supplier hasn’t a clue on how the antenna will be installed.
For example, its common to mount to a vertical tube but then what’s it’s diameter? It could be a outrigger from a tower and be a horizontal tube (again what size)? Alternatively it could be a bracket secured to a structure like a chimney.
Reflecting on your comment I realised I tossed the clamps that arrived with my antenna on a pile of similar bits and pieces as I build my own clamps. I prefer either stainless steel hardware or Hot Dip Galvanised bolts, nuts and clamps rather than the electroplated versions which rust very quickly. (Example The BIG and SMALL ANTENNA topic part 1 - #451 by BoRRoZ ) I can get a range of clamps sizes from car exhaust suppliers and fabricate from there.
I wonder if there is an opportunity to design and sell a set of universal antenna clamps for Lora systems?