The beauty of a portable A/C unit is that you don’t have to heft it into a window and block off a valuable source of fresh air for keeping paint fumes at bay. Instead, choose a model with a low profile that you can tuck under a table or against a wall when not in use — a model with casters for maximum maneuverability is ideal. Choose a high-powered unit that will condition at least 400 square feet of space and move it where you need it for maximum comfort as you work.
Let’s be clear about one thing: No workshop is perfect for everyone. If there were, I could simply give you a precise plan to follow with clear dimensions. Every person who comes to the hobby, avocation, or profession of woodworking has his own particular collection of tools and his own peculiar work style, skills, and desires for the kind of woodworking he wants to do that gives him a unique approach as to how he will lay out a shop: where the tools should go, where lumber and supplies are stored, and how much bench area he needs.