This is the way to do what you're doing. I have seen it done.
I don't know enough to give "real" advice, but a couple of things to consider-
Consider framing it in like an overhead door, and to a standard overhead door dimension. That futureproofs the whole thing a bit should the size of your machines OR, just as likely, if the size of your work changes.
Consider splitting it in half. Two swing out walls. Framed in, insulated walls are a considerable weight. By that merit, it might actually make things similar.
I think you said this, but WITHOUT compromise on any headers, consider any (reasonable) effort to make it as tall as you possibly can. Short machine tools with hoisting mechanisms above them get very tall, very fast. Tractor buckets or loader arms with attachments are the WORST in this department. Every inch of headspace you can get is a bonus that you will use one day. (I say that, but I'll also be the first to say that "some" hydraulic hoist is a helluva lot better than no hydraulic hoist).
Consider your local tax appraisal (This is expensive taxes on a door in some places....), your heating/cooling load, and see if a proper insulated overhead (not roll up) door might be plausible. I hear what you're saying about doors, but there are many of us who work in front of a disused or seldom used overhead door daily. That could (If and only if it fits your life), be an "easy way out". A machine that's on a riser which fits a pallet jack can disappear pretty quick if you wanted it to.
Do you have much first hand experience with pallet jacks? They're quite versatile. Especially at 100 miles per hour like the LTL drivers do. But if you're moving slowly and carefully, and especially slowly and carefully with topheavy loads that shouldn't be on them--- (I'm guilty too, no judgement here......) please take this advice- SWEEP THE DANG FLOOR..... Seriously. If you follow no other precautionary advice about the tricycle effect, keeping center of mass towards the nose wheels for top heavy things... All those are good and necessary advice, but that's the one to remember right there. Sweep the floor. After that, and after you figure out how to store it without wasting space, they're amazingly versatile tools. Four out of five chiropractors would more than likely recommend everyone have a pallet jack.