I can't say I'm a fan of attaching something like this to a safety critical component like a brake or clutch reservoir, but I've yet to hear anyone report anything negative from anyone that's using them. I prefer the lever perch approach myself.
But to your other question, RAM makes an arm which might suit your needs.
RAM® 18" PVC Pipe with Single Socket Arms
They can be had in different lengths from 14" to 24". They come in pieces - you have to glue the octagon button onto each end of the pipe so you have some opportunity to cut it to the length you need. It's been a while since I assembled mine, but I have a vague recollection that there's an X-rib which runs the length of the interior of the pipe making it quite rigid. Photos on the RAM website don't show that, so I could be dreaming.
Pipe diameter is not listed on the website, but I measured mine at 27.5mm or 1 3/32".
Here's a picture of my 18" version laid over my clutch and brake reservoirs. I use this as a mast on which to place my GoPro camera to get some 'approaching, but not quite' over-the-shoulder views of my rides by mounting to a RAM ball at the rear of my ST1100. Still looking for a solid mounting method for the rear of my 1300.