I'm looking for a new map loophole at the Junkyard. and having trouble destroying tunnels,
The bug tunnels? You can sometimes find material that can be used to block the tunnels in the "?" mark spots. If you have it just go to where the bugs emerge from the ground and you will be asked if you want to use it.
If you mean (freeing) the underground tunnel between the islands: get a high endurance and high strength and do repeat removing the debris until you succeeded. It can take maybe 10 times doing it. Use the energy drink to remove the "tired" status in order to be able to continuously repeat freeing the way.
A new map loophole?