You're kidding yourself if you think you're going to be doing dodge+burn setup/experiments at 56"; it's madness. You'd setup a print at 8x10" or 16x20" or whatever and run through a handful of different dodge/burn schemes to find a tonal balance that you like and THEN scale the print up to final size using a spot of arithmetic and then a bunch of testing because your paper reciprocity failure will be noticeable. Most people seem to typically produce 3 to 5 work prints for a complex final print and the cost of those at your final size is immense, not to mention the time and unwieldiness of processing 5 sheets at that epic size.
Originally Posted by Old-N-Feeble
Have you even handled a piece of paper as large as you're proposing? You're probably going to need a crane (wooden bar with clips on a couple of strings) to transport sheets gently from roll to enlarger to developer without inducing crinkles. 16x20 is difficult enough by hand.