Cheaper route to go rather than multiple head or mutiple unit mini-splits might be a 'package' unit. Everything (compressor/evaporator) comes in a single unit that sits on a pad outside. You basically plug it into power, connect a thermostat and run it.
GPC1536H41 - 3 Ton 15 Seer Goodman Package Air Conditioner
You would have to run a small amount of duct work, it has to have a supply duct and return duct run to it......but that is fairly easy in a wide open shop situation. Run the supply up a wall about the middle of the shop long wall, and simply let it blow out at ceiling, or run a short T and let it blow toward both ends (you could add the T later as you see how it performs). The return would be a real short duct run from down low on the inside wall to the unit sitting just outside.
The big advantage of mini-splits is not having to run any duct work....and you can get far better SEER ratings. But when you start looking at the price difference, given the amount of time you might use the unit, you may well find one of these is a whole lot cheaper in the long run.
Also, since this a wood shop, you're gonna generate a lot of 'fine' dust....even with a good dust collector. The package unit would have a pretty easy to access air filter in the return down where you'd be more likely to inspect and change it versus the little screen filters on mini-split units on the inside head. That fine dust is gonna play heck on the coils on an evaporator if you don't keep it out. I was envisioning a 'double' return where I'd mount two filters side by side feeding into the return to give me a lot more filtration and return air movement. The wood furnace I have in the shop center has a plenum box built on the back with a filter mounted in it, and that filter I have to change REAL regular in the winter time when I'm working in the shop or it plugs plumb up.
I've considered the same for my shop...it's 35x75, with the main part inside open to 60' length. Has 8' side walls, then the ceiling slopes up at the first angle to a flat ceiling at 13', then back down the other side the same. On the upper side (opposite), the wall is cinder block below grade for 4-5' of the 8' vertical wall. Perfect spot to plug in a package unit sitting just outside, short return duct, and not too much supply duct either....up the 45 degree slope inside, run a T on the flat ceiling blowing toward either end of the open part.