There are twin-hose portable AC units on the market - I’ve got one to supplement the rumor that is air conditioning in my home office and has been trouble free for 4+ years now. They avoid the problem of running conditioned air over the hot side coils and operating at negative pressure.
I recall that the DOE - or some other regulatory agency - changed the rules around rating portable units and their BTU ratings have dropped significantly since a few years ago.
Portable AC units are not as effective as window units and mine struggles to keep the ~150 ft² of office within 10 degrees of the rest of the house; some of that could be the un-insulated garage door and possible lack of insulation in the vaulted roof in the room along with generous western and southern exposure. Should I ever turn my shed into a workspace, suspect I’ll just get a cheap window unit that operates as a “through wall” unit.
I used to have a sketchy arrangement in my office like that using the window unit down the hall in the bedroom.
Duct at the bedroom:
Mid-duct booster fan:
Occasionally this happened:
I also had a box fan at the far end trying to help out but at the end of the day I just went with this: