First, take the items you want to not trade out of your bank into your inventory.
Then make sure you have no meseta in your inv, it just makes it easier. Then do the dupe trick up to the deposit/take window. (if you take it out after, sometimes the person doesn't see the items in the trade window)
With the deposit/take screen still on your screen (you never take it off), have someone open a trade window with you, or open one with them.
When scrolling through windows, always use the up on the d-pad, this makes it so you are always doing a deposit->meseta. If you ever need to back out of something, make sure your on the meseta/item screen or you will back out of the dupe trick.
Next add in the items you want to ghost trade into the trade window. Get the trade straight and backout the items you are not gonna pretend to trade.
Then go to "verify item" in the trade window, and "deposit" on the bank window. Depsoit all the items your gonna trade. This makes it appear in the trade window, but nothing is really there.
Do a final confirm, you get thier items, they get nothing. Muwahaha!