The whole point of using a thread locker is so you can use minimal torques. 15-18 in lbs. is 1.25-1.5 ft. lbs. That is not very much. In fact it is very little. Thus using thread locker to prevent them backing out. and of course, light torques don't crush the aluminum tubes we all use. I keep it handy as most times I'm installing rings I'm also installing a base. If you think base screws don't loosen up, maybe you could give me your technical background on how to properly find drag torque, what sequence torque to use and if you need to use step torque, or just get it all in one fell swoop. As for what a bolt/screw holds for preload there is no way to measure that unless you have instrumentation on an individual item you are torquing. And yes, I've done that many times but never in such a light application. For this application it's done in a laboratory and the information is then accompanied with each product that uses it. Suffice it to say you do not need to find preload as that has already been found and the applicable torque information with the chosen screws should be with your rings or bases.
FWIW, yes common sense should be applied here. You never need a ton of thread locker. But using the soft thread locker, blue or purple, you could goop it on there and it ain't gonna make a hill of beans difference. It'll clean right off with some knuckle grease. It will look bad, but it isn't holding anything. The only part of it holding anything is what is on the threads. So, that's all you need.
Should I get my shovel? So we can make even more of a mountain out of this molehill?