Greetings!   

I'm a Master Tier subscriber, so I have access to the DM tools, but I'm running into a snag.

I will be running a horror campaign, so I want to incorporate the Dread and Sanity conditions (as found in the 3rd party sourcebook Petersen's Cthulhu Mythos), but I can't see a way to edit the character sheet to add them, nor is there a "Create Homebrew" option that I can make these conditions from scratch.

Has anyone figured out a workaround for this yet?  

Thanks in advance!

Most times, if you are looking to add a permanent, or mostly permanent effect, the best way is to homebrew a feat or even an item, that mimics the effect. 

I don’t know about that 3rd party sourcebook you mentioned, but I did run a Cthulhu inspired campaign for about 2 years. I used the Sanity and Madness optional rules from the PHB & DMG. I created a feat for them, if you want it I can share it with you, just send me a PM with a “join link” to a private campaign for two.

At the bottom of the character sheet in the Skills section there are 3 blank lines to add things.  

You will just have to write them in and track them manually. 

Another option could be to create a homebrew item that has the traits your looking for and add it as an item