Not sure about the M101A2 I would have to look at it. But the boat trailer should have a hole going through the tongue for a pin to be inserted. You will kick the snot out of your brakes if you do not. I have the same set up on my boat trailer. As soon as I back up 1 foot or so the brakes start to drag real bad then stop. Once you find the hole, get a pin and put it on a short cable so you have it on the trailer all the time. Do not use the safety pin from the latch . Bad things happen when that is taken out.
I seen a guy switch them then so he could back down the ramp. He backed down the ramp without the safety pin on the latch so he could back up/down. Weight shifted, trailer popped up,no safety chain on, lower unit smashed into the ground, trailer and boat came back down taking out the rear quarter of his brand new Escalade. Sometimes it's more fun to hang around the ramp then it is fishing.