Not unusually thick at all. It's done far thicker all the time. Xan you do it? Sure, if you read up on the process and have some help. It's nothing more than Portland cement, sand and water.

You'll need to establish your perimeter height, level and consistant throughout the entire area. These are "screeds" and can be 1x2's attached to the walls or set on the floor. If the width is over 6 ft. or so, you;ll need to have another screed running down the middle of the area. These are removed after the mud is in and they get filled and tamped down. If this is done after the mud has dried, use a margin trowel to "cut" the boards free of the mud (although earlier is better if you can easily reach them without messing up the "area mud")

Once the screeds are out, paint some very runny thinset on the edges and floor where they were and pack in some fresh deck mud. This assures a good bond from old to new.

You can also build your guides or "screeds" from the same mud mix. Link shows the screeding process. Also, note how this this bed is!

Here is a link that might be useful: Floor Screeding with a straitedge

Thanks!

So do you lay the mudset let it harden and then do the tile on top of that, or do you do a small section of mudset, tile, then move on to the next section?

Some Old-Timers used to do small areas like a shower, then while the mud was fresh, sprinkle a bit of cement or morter over it, wet it slightly and set the tiles in it by tapping them lightly. This is just trivia for you. Don't do it like that! The area is far too large.

Let the mud harden up for a day or two. Take a rubbing block or a brick and move it around the surface gently to erase any ridges or imperfections, vacuum the surface and set your tile.

That makes so much more sense. Thank you!

You're very welcome.....