The cheap Chinese plasma cutters are the bees knees for cutting down sheet/flat bar/weird shapes.
Get yourself a metal speed square and take the corners off the back of it and you have a good, square straight edge for under ~6" ish cuts. You grind the corners off to clear the torch it's obvious once you try it.
Longer, straight cuts 3/16" flat bar makes a good cutting guide and with the ag60 torches the cut will be about 3/16" away from the guide(if you're not using a standoff or wheels) so it's quick, easy & repeatable.
I've cut a shit tonne of 1/8", 3/16", and 1/4" with mine. For shorter cuts I doubt you'll have much problems with air supply. If you're cutting feet at a time different story.
As mentioned make sure air pressure is (usually) 65psi or less. Or you could blow the hose out of the fitting internally. Mine has a regulator and I just leave it at 60 or 65 at all times but with a smaller tank you may want to try less cutting sheet metal.
The ag60 torches(like what comes on that unit) also have 40, 50, and 60amp consumables. If you use 40amp (.9mm I believe?) it should use less air(smaller hole)
We had a miller spectrum 375 extreme at my last job and my sub $200 herocut with AG60 torch would easily out cut it..... In both thickness & how clean the cut was.