Loading more than six chunks at once

Solution 1:

While in the shower thinking about how to best implement a function, I stumbled across a possible solution for your problem: have many smaller command block chains that command a couple chunks around them. You could probably testfor a player and then set the blocks accordingly. The SCP you referenced will likely not have super large rooms, so you'd probably be able to get away with this system.

I'm going to keep my other answer up, because other Googlers will end up here, and because it will work in the future, but for now we're stuck with Vanilla mechanics.

Solution 2:

In order for that to work, Minecraft would need to have a strong modding community.

Luckily for you Minecraft has one of the biggest modding communities. The mod you are looking for is called FTB Utilities. (There are other mods, but this one is closest what you want, I think). You will need a mod launcher, and this mod has a chunkloader utility that keeps chunks loaded. All these things should be easy to Google and set up, but if you need more guidance ask and I'll add to my answer.

One caveat: You will have to use the Java version of Minecraft, as that is the version that is modable. The Bedrock modding community is getting close, but not quite there yet. One interesting project to follow is https://nukkitx.com, perhaps you could ask their forums to see the plausibly or even solution of a chunkloader plugin at their stage.

Your save file will be compatible with Vanilla Minecraft if you switch back, but the chunks won't be auto-loaded anymore.