Luckily, there's finally signs that Blizzard means to bring us relief. Eyonix mentioned this morning that they've begun to look at possible ways to relieve the tabard space conundrum. It looks like the concept is still in the early stages, and Eyonix specifically said they have no ETA, but it may be coming, which is good news enough. I'm still advocating for a simple drop-down menu of tabards similar to the title dropdown on the character screen, or maybe a way to select a faction from the reputation screen to be your tabard of choice.
But however they do it, I'm looking forward to it. I enjoy flying various colors at various times for RP or fun reasons, so being able to switch swiftly should both make this easier and championing on the fly easier. Here's hoping we get an ETA soon, and that it's sooner rather than later.