Oh, I feel your pain! I went through similar experiences with my younger daughter. She would show up at our bedside in the middle of the night, want to climb in, and invariably I was the one who had to drag herself out of bed and take the kid back to bed! If memory serves me correctly, there was one desperate time when we contemplated installing a bolt on the outside of her door to keep her in her room at night! Crib tents did not exist when my kids were young, but they sound like they might be worth a try. You are doing the right thing with the "silent return"...don't reward his behavior with conversation or cuddling. My older daughter was so adept at unzipping herself out of her footed sleeper and ripping off her diapers that I had to use one of those special diaper pins on the sleeper's zipper to try to stop her from unzipping! So I don't know if a sleep sack will do anything to stop an agile 2-year old. Sorry if I can't offer any suggestions...you are doing all you can and hopefully this phase will end soon. Keep up the "silent treatment"! Oh, here's something that worked for my kids. Have you tried playing lullaby music each night? My daughters LOVED Joanie Bartels' "Lullaby Magic", and also the Rafi songs. I tried to keep to the same routine by turning on the lullaby tape after we had read, cuddled, etc. I would then say "Night night", dim the lights, and leave. The music was very comforting to them.
Good luck...hope this helps!
Sincerely,
S. A.