My take on the solo easter egg for this map is YES it can be done....no one has done it yet...Definitely does not mean it isn't possible. I have done this with 4 players and I am still playing around with trying to activate the eclipse solo. All of the other items needed to do the easter egg solo are indeed still in the map.
Example(s); the tunnel you have to lead the fire zombie through still has the gas wheel that is turnable and the lever beside it. When you are in the waterfall area near the backside of the map, the stone that says "Don't hold []" or X if xbox, is also still their.
There is one radio located near the MPL that explains how the original founders of the temple got locked inside. The other radios appear later after completing further steps in the easter egg. The holes in the tunnel that need to be plugged with spikemores are also still their....AND the buttons on the wall still come out when power is restored.....Just to name a few
(The 4 gongs btw have to be hit in a certain order during the eclipse. There are 8 total, after hitting the correct 4, you will notice the TreyArch symbol above the crystal ball near the top of the map where the mine cart begins. Hitting the incorrect gongs will result in a high pitch noise.)
To sum it up, and after hearing an interview with one of the developers, I feel there is a way to do it solo. I don't believe that all of these things would be placed in the map solo if it wasn't attainable. SO KEEP TRYING. The hardest part is going to be activating the eclipse, the rest is cake...
If anyone wants to join a game/add me, my username is ITALYv-tec1994
If this confused anyone, you should probably check out an online video of 4 people successfully completing the easter egg. This will give you an idea of what needs to be done, and possibly what steps could be condensed to a solo player....
-Vin