> I'll stick to 'civilian' method
Oh, there is nothing wrong in "military" method. Moreover it can be preferebale in many situations. It is naturally more convenient in computations/comparisons or processing massive data. Even civillian will switch to it under train schedule table, for example.
It is a little bit unnatural in everyday speech, but very very little bit (as I said before).
> So how would I say 'from 8.48 to approx. 8.30', using the 'no-military' method?
This is another good example. We can say:
"с без двенадцати девять до примерно пол девятого".
But "с без" - two particles in a row without vowel between them sounds and looks even ugly.
"с восьми-сорока восьми до примерно пол девятого" sounds good.
In fact "civillian method" works better with round numbers.