there are a couple of cheesy ways to break the chest that don't trigger them. I do not know if the cart works as one of them, but anything that breaks it without them being able to relate it back to you should work, they don't care if you loot it, they care if you damage the box.
the most straightforward way is to just kill them. Wear your root chest for the archers and a fire potion for the wizard (and your frost cape, of course) and its not too bad if you scouted and didn't see a ** guy. Find some cover, and ambush one before they can react, then just deal with them and collect your extractor. You only really need 1. I have a glut of sap with only 1 after just a few hours of play. Its likely you will get 2 or 3 more over time due to mobs trashing these guys and leaving you their stuff.