from what my lowes had either the rivets were too skinny or too fat or too long. They had these smoothe topped caps that would be great except the 3/8", 5/16" are too big and the 1/4" too small. I liked that this one had a flange so it covers some of the rubbed off paint from mirrors.
I'm curious about the RAM mounts, and why they are all the rage?
Personally, my requirements for mounting a phone on my bike would be a waterproof housing, and maybe something that prevents overheating, and it's got to stay on. I use my phone as navigation and music. I realized on my last trip if i were to lose it i'd be pretty screwed.. but you can't beat the level of information and road detail you can get on a phone.. I'm sure there are some GPS's that have it.. but with so many negative comments about gps's and the turmoil of downloading the most updated maps constantly or subscriptions, i've been too skeptical of that route. I'd love to hear of a good option though.
I do get...go exploring... a lot on my trips because i don't have the phone mounted so have to rely on audio cues to decipher which road i need. btw i use osmand and furkot to route my trips create gpx files and turn by turn navigation.