PUGs (Pick Up Guildies, in this case) will never be a sufficient solution, we all know how unreliable randoms can be. Implementing alliances is a much better long term solution, IMO, but it doesn't seem to be a priority to ANet at the moment
An unofficial, self implemented alliance between smaller guilds might work, but it's patchy as well, while an understanding with some of the local big guilds could be worth the effort. However, this is a local solution, for our specific problem; other small guilds won't necessarily have the luxury or ability to do this.. I do hope that ANet realises/notices how much this screws the small guilds over, and does
something to make it a bit better.