I want to mount a 55" TV on an exterior wall of an energy efficient house. The wall has a support beam bridging a large section with continuous solid foam board across a wide area. 2x4s sideways(3.5" side contacting drywall) on the inside hold 1/2" drywall.

The wall mount uses 3" bolts meaning 1/2" drywall plus 2.5" into wood is expected. If I were to go into these studs, only 1.5" would go into wood.

Options I can think of:

1) ignor issue, install conventionally and have less than spec strength.

2) take advantage of width to put in 2 bolts across in each stud

3) replace drywall under mount with plywood(1/2" enough or need 3/4"?). Plywood would give extra pullout resistance. If 1/2", could finish to match wall and be largely invisible. If 3/4", it would stick out slightly, but could be finished to match wall color.

Mount is tilting Rocketfish model for up to 70" 130 lbs displays.