I would personally go with a commercial unit, seal the room, and supplement CO2. Those regular units are far from efficient. You see a lot of complaints about smell...not only is smell leaking, but nicely air conditioned air is getting sucked out as well. One hose...two hoses...it doesn't matter IMO. Some units come with an internal carbon filter so you might not be able to smell anything right off the bat, but unless the unit has two COMPLETELY seperate chambers it's going to exchange air...smelling up an outside area...while costing you money. Kwikool and MovinCool make sealed units, but Ideal-Airs are the most affordable. Some people prefer mini-splits over commercial portable units...they're usually about half the price, they take up far less space, and you don't have to cut 12"-16" holes for exhaust ports, but I personally don't like the idea of having condensers outside. IMHO, a gardener should completely seal their room and supplement CO2 once they can no longer control temps with air exchange alone. There's no point in exhausting an air conditioned room IMO...and you can get away with (slightly) higher temps once you introduce CO2...(hopefully) allowing your air conditioner(s) to cycle (a little) less often.