@jehlybean Sorry for the delay. I called them the other day but the rep I spoke to couldn't find my order. I believe the reps I had worked with didn't enter the custom plate they made me into their system, but did it as a customer service resolution for me. However, I do believe if you call them and give them these specs they'll should be able to help you:
Item SKU: 65-2455 (this is a Solid Aluminum Plate: 6.350mm thick, the proper thickness for the 8mm countersunk you'll need to drill into it)
Dimensions: 180.32x190mm
Machining:
1) Full Edge Radius
2) 18mm Corner Radius (on all 4 corners)
The corner radius is what they don't have listed on their store page and is the reason you'd call them instead of ordering online. Worst case scenario, if you don't get the corners done, you'll just have little corner edges poking out where the rounded corners of the Rhino end. Not a huge deal. If you do get the corner radius done, the plate will perfectly match the underside of the Rhino.