When I think "drying out an APA" it is more a function of mash temperature and attenuation of the yeast, no? I believe you are talking more about creating dextrins and mouthfeel with the crystal malt? I think it is honestly a matter of personal preference. With the WLP007 at 152F (knowing that yeast rather well) regardless of whether you use crystal malt or not, I would be surprised if you don't get near 80% attenuation. Which most people would say is "dry," but will it be thin and flabby? With 50% Munich, I doubt it. I recently brewed a Nelson Sauvin APA with 80% MO, 10% Munich, 6%Victory, and 4% Wheat. It turned a deep golden copper (per BJCP APAs can border on being Ambers, there is some overlap in the style) with nich malt complexity, but finishes crisp and dry. I am thinking this will be my base malt recipe for APAs from now on. Certainly, hopping rates can create some of this "dry" mouthfeel from the tannins and the bittering provided by the hops. It is all a function of balance. I suppose you could always brew 2 recipes with the same hopping regime: one with 50:50 2-row:Munich and the other with 80-90% base malt, and 10% crystal with some other combination of malt (maybe, 10% Munich?). Then see which you like more?