A:
You want to take them with you. If left overnight you risk losing them, another boat wrapping them in thier prop-wildlife getting caught in them etc.
Go ahead and mark the spot you have found in your GPS if you have them.
If you don't have a GPS-use a notepad to take notes. Choose a landmark close to the spot and make your notes- Like 100 yards off the big rock-also note the water level as it can change.
By the way-Bass Pro has very reasonable hand held GPS units that come in handy!!