Sorry if this is the wrong forum for this question, but its as close as I could figure!

I am remodeling a wall to accommodate my flat screen TV. I hope I can describe it sufficiently.

The brief background is this is a block wall which was once an exterior wall, before the carport was turned into an interior room. I've decided to utilize a window opening to mount my flat screen in such a way that it can rotate between the two rooms.

I have a ceiling mount which I will be hanging from the top of the inside of the window. To do this, I have a 2 x 10 across the top of the window space to which the mount will be affixed.

Here's where it gets complicated... The power and HDMI cords will run up the mount to the space above the TV--super clean and pretty! I have a receptacle available there. BUT...I need to be able to access the receptacle!

The TV with mount weighs 60 lbs. The 2 x 10 will be resting on the top end of another 2 x 10 on one end. The other end will be screwed on angle into the face of a third 2 x 10.

Can I cut a trap door to allow my hand to access the receptacle without sacrificing the load bearing strength? I think a 4" opening should be sufficient. Does it matter if I make this cut-out at the end of the board or in some number of inches?

Thank you very much for any and all input.

Coraxi