help with tongue/receiver interface?

[oldboyscout]

I'm working on a trailer with a 2x3 x1/8 tongue and want to attach a 2x2 x 1/4 receiver to it (to interchange couplers/eyes etc). Should I notch the 2x3 at 2" and put the receiver over it? Notch the top or bottom of the 2x3 and inset the receiver? something else?
I'd appreciate any ideas.