As long as you've got it taped off use your normal gun,cut back on the fluid,run your fan size down a little,leave the pressure up some and use the right temp reducer.If needed over reduce it a touch.What you want to do is get pulverizing atomization with the big gun,even if it takes 2-3 coats to cover the edge will be minimal.Think of covering the floor with BBs or bowling balls,the BBs will cover in less coats and be thinner.That's what atomization is all about.Brushes an detail guns are great but you can work around them to a point until you get one.