I don't know if there's any reason not to do this, but if you're really lazy you could just throw the spacers on over the outer lock nut. It will be annoying every time you have to put your wheel between the dropouts, and you risk losing them when you remove your wheel. It has worked fine for me in the past, I have been known to do this for various reasons but usually only temporarily.

You can just use the bolts to pull the dropouts together, but I don't think it's the best idea. I have also done this with no ill effects but it's so easy to throw a couple of washers on that it's not even worth doing. Also, I think it would be a particularly bad idea with an aluminum frame.