Running galvanized pipe along wall

I have a need to run about 40' of 1" galvanized pipe attached to an outside wall, with two elbows in the run to accomodate a crawl space vent that is in the way. This may seem like a very stupid question, and in fact maybe I'm missing something, but it seems like once I start attaching pipe to the wall, I will have no way to get a wrench in there to tighten the fittings. I've done plenty of surface mounted work with EMT, which uses slip-in compression fittings, but not with rigid pipe that I have the crank the hell out of. Maybe if I leave the straps a little loose, the pipe will have enough play in it to pull it out far enough at the end to get a wrench on it? I know it can be done, because I've seen it done on plenty of buildings, but I just can't seem to wrap my mind around how; is there some kind of trick to it?

I can't use any other type of material because this is for gas, and galvanized steel is required outdoors.