My truck started out with the same A2 winch plate as you have. From my understanding I could have just used it with the winch, but with how the brackets are set up I'd really need to put the bumper extensions to install it properly and to be able to reach the clutch lever.
There always seems to be some confusion around the M1123. It's actually an A2 variant truck, the same as your M1045A2, the big difference being it's a heavy variant truck like the 1097A2, but doesn't have the airlift bumper because the marines didn't want to lose the departure angle, and they pretty much all have the deep water fording kit already installed. It's not the same as all the other M11XX trucks that are ECV or REV.
Here is a pic from one of the facecrook groups that shows a Warn winch mounted onto the A2 winch plate without the extensions. I assume it's a Warn from the Warn sticker, but can't verify what one.
View attachment 849752
There is also a custom plate made for the Sherpa 24V winches over at blackdogcustoms.com , along with frame extensions.
blackdogcustoms.com