A "backer" doesn't have to be in back. It can be a "fronter." You can take a piece of plywood, bolt that to the wall using molly bolts. More than just at the corners. I used the shortest ones, but then got longer screws so they'd reach through the 3/4" ply), and then mount the TV bracket to that using countersunk carriage bolts coming through from the back. It just has to be large enough to spread the load. Best if you have vertical room to work with and make it reach near the ceiling where the wall/ceiling joint adds strength. Because, if using an arm mount it will try to pull out at the top so the more height for the "fronter", the less force. Worked for me, it's about 12" wide by 18" tall. Baltic Birch (or "Sande" from a HD/Lowe's) ply looks much better than the common stuff if finished with stain.
Without more detail, further is hard to say. Even if your's has aluminum studs, that probably only applies to exterior walls.