I'm taking a gamble and bought the Rough Country tray, and after taking measurements of it once it came in, I ordered a Sherpa Steed 17k winch. I believe that with some slight modification to the tray, the winch should fit. If not, then I'll buy a welder and will learn some welding. I looked at Superwinch, Sherpa, ComeUp, Bulldog, and more, but for a winch at least 15k, the Sherpa seemed to be the only that could be a potential contender with this tray.
That said, if someone is looking for a quality 12.5k winch, I believe that the ComeUp Seal 12k Slim would fit with no modification. That's just from their published specs and taking measurements from my tray. However, ComeUp is a foot-forward mounted winch, so they don't recommend mounting it like it would be in the RC's winch tray.
I've never had a Sherpa winch before, but once it gets in, I'll try to document whatever modifications to the tray are needed for it to work, if it's even doable.
That said, any idea on their delivery ETA to the US?