Very Specific Stand/Mount Need for 55"

[MouseHouse55]

Hi everyone! Hoping your experience can solve a problem I'm having. Short version: I'm looking for a mount that attaches to the top of a cabinet and telescopes out to the viewer (essentially making a 90 degree angle) for a 55" 930E.

Longer version: I have built-ins that hold up to a 46". I planned to modify them to hold my new Sony 930E, but it turns out that the wood I was going to carve out to make the tv fit is load bearing for the upper cabinets. So I'm looking for some sort of mount that attaches to the cabinet base/top where the tv would normally sit, and then telescope out beyond the existing wood supports. I feel like that is asking a whole lot, as the tv itself it 65 lbs., but I thought I'd check!

If you have other ideas, I'll certainly take those too. Thanks!