Not sure about the new winches but years ago, the 3K winch fit in the "cubby" but the 4K didn't. That was one of the main reasons I went with the 3K (Ramsey).
My winch will drag my RTV with the brakes on so that's enough power for me. Remember, there is always a "weak point". I'd prefer my winch to bog down/stop than it be running great and something else on the RTV is the weak point and breaks.
I'm a big fan of the synthetic rope. Besides being easier to handle, it doesn't store any energy so if it breaks, it falls to the ground instead of flying back at you. If you do use the rope, you should switch to a Howse fairlead (instead of the roller) since in theory the rope can find it's way into the corners of the rollers and get damaged. I haven't switched but I keep my pulls as straight as possible.