On the rims I am not sure yet. I Did some reading and it
Yes. And a lot of people have climbed the Alps with a 39x27 cassette back when that was about the only road race option there was. Therefore, that is all you need. Never ever put a lower gear on your bike! But today lots of road race bikes use a 34x32 in the Alps. You are advocating zero margin. Take it right to the edge with absolutely no room for error or chance. Nothing extra. The asymmetric gives you a cushion, extra margin so you are not right at the edge. When I go up to the edge of the cliff, I prefer to have an extra foot of space for my feet. You advocate putting your feet right at the very edge and hoping you don't lean the wrong way and fall off the cliff.
The blurb about gear ratios is off topic and irrelevant.
You make it sound very dramatic, but there is no such problem. I am not sure what your experience is, but most if not all builders will tell you that an asymmetric rim is nice but not essential. If the OP can buy a robust asymmetric rim that fits his needs, then great, otherwise I would go for a robust but symmetric rim over an underengineered but asymmetric rim for his needs.
And that's all there is to it... nobody is standing on the top of a cliff, nobody is about to die... all is fine