I want some AD earlygame, but adaptive runes refuse to work for me

I don't have time to write too long of a post, but I have been playing support for many years and I always take a little bit of AD in my rune page, depending on the champion. Despite Nami, Sona, Soraka, etc. being considered AP champions this season, we autoattack a lot in lane, and it would be nice to be able to choose to have at least some AD to back that up in-game. Unfortunately, I haven't been able to figure out any way of turning adaptive runes into AD runes for my support champions without buying a long sword or a Doran's blade, and that disappears as soon as I decide to buy a spellthief's edge or any other item that happens to give some AP. But having to play many matchups and styles, with many different ADCs, sometimes I want to have the AD option (in fact, I usually do!). BUT NOW I CAN'T [sg-soraka]**[sg-ahri-1] So - does anyone know a way around the adaptive rune bottleneck for 'AP default' champions? And if not, can we ask to be able to choose a pre-set AD or AP for adaptive if we want to? I feel like adaptive runes were meant to make champions more versatile, not less so.