Getting to Terramorphous Peak Cult of the Vault symbol?

I've been trying to get to the Cult of the Vault symbol that's "under the platform you drop down from to enter the arena with Terramorphous" (description taken from this question), and have found some videos showing how to get to them if you have a friend in your game. However, I mostly play alone, so the trick shown in the video isn't really an option for me.

I've tried to get Terramorphous or his tentacles to knock me up to the symbol, but haven't had any success so far. Has anyone ever got to the symbol while playing solo, and if so how? Does a reliable method of getting knocked up to the symbol by Terramorphous even exist?

Edit 12/25: I'm playing on the PC, so I also don't have the option of using a guest player in splitscreen to reproduce the trick shown in the video.

If you're playing on a platform that supports splitscreen, this can easily be solo'd by jumping down with your guest first, and then jumping down with your main character just before the gates close, look up and discover the symbol.

While I tried getting this with a friend the trick I did should work with one player as long as you can land on the fully-closed track.

All I did was run or jump into the wall repeatedly before/while the grate was falling open. After several attempts (I was actually just trying to jump after the grate opened or before it closed) I managed to glitch through the wall and briefly got access to the vault symbol. It's not very reliable, but I've heard of others getting the symbol this way and if anything it seems no less difficult than doing it the normal way with two people.