The find, the design, the demo ( I love demo), the building, and sourcing of materials at deep discount ( love this more). 

I would do all the demo and carpentry including installing the backer board and the tile. 

I've learned that I can probably save the most money in demo work myself after I talk with a GC.

Then you will have to pay the roofer to demo and reinstall which is where the $$ is anyway.

I just had a great Call/Demo with TurnoverBNB.

Our team is usually first in and last out, meaning we handle demo & scope, bring in the subs to do the trade work, then we handle finish work. 

Rural areas have weak demo's.

Things will change as you start demo work.Lastly, keep changes to a minimum.

After the demo day, and 2 others of work being done they are demanding that we put the toilet and sink back in so the bathroom is usable, and to stop all work until they move out or they will not pay their last month's rent.

One thing that works in your favor, is that if you plan to demo all the plaster and put up new drywall, that makes rewiring and adding insulation much easier.