I don't have a Aspen Trail but our Main TV entertainment center are similar. I am assuming that your trying to put the TV inside the recessed TV area. This just would not work for me, so I decided to mount the TV so it would be flush on the outside of the TV cabinet. This meant I could go from a 23" TV to a 40" TV.
First you will want bring your slide in and see how much space you have between the slide and TV cabinet. You will need at least 2" of space OR the thickness of your TV with a little to spare.
I used a double articulating arm TV mount. This mount will pull out and will allow the TV to sit outside of the TV cavity. When mounted you just push the TV in til it is flush with the cabinet.
I used a good electronic stud finder and found that the entire area was backed with solid wood (yours may be different to so check it out)
I centered the mount and used 1/4" lags screw 1/2" long with washers.
I also installed four small metal brackets with nylon straps to secure the TV in transport.