need advice for this DIY woodworking project?

Woodworkers, carpenters, contractors, etc., I need your help.

Background: I have two 2x10 wood boards that I need to connect. When completed, the boards will sit on their long edges, connected along the 10" ends as shown in my crude drawing (#1 on the left). That weird curly thing is supposed to show how the fasteners will be used. Of course they will not be visible, and there will be more than one of them.

When finished, the "board assembly" will be cosmetic. It will be attached to something else, but it will not bear weight or hold other things.

I am looking for a purchasable item to serve as a decorative cap or covering, which will cover the corner where the boards meet. I want to cover the top edge, and all the way down the sides, at least a few inches from the corner in both directions.

Basically I want it to hide the seam or joint in its entirety, so no evidence of the two boards meeting is visible. Just the top edge and outside part of the corner edge need to be covered. The inside corner and the underside edge are optional--they can go either way.  

But wait, there's more. When I attach the two boards together, the joint will not look exactly like the #1 picture. One of the boards is necessarily a bit short, and the actual board connection will look more like #2, on the right hand side of my drawing.

This is another reason why I wish to hide the connection.

Any ideas? What products exist that can be simply attached to the assembly after the connection is made?

Thanks!