I remembered that there was a way to turn off blood and bloodstains by right-clicking TB in the Steam library and going into properties, but I forgot how to enter the command in the launch options. What's the correct way to disable these features?

Uhm, you can type /opt blood 0 and /opt bloodstains 0 ingame.
It should do the same.

Yes, but I don't want to manually enter it every single time I open up a client.

Do you have the Remember game rules option checked?

Yes, I do have it checked, but that seems to only work for the main graphic options that you can find in the main options menu. For specific ones like the ones I mentioned, or bruise even, I have to manually enter commands to disable them each time I open a new window.

Oh auto changing options on startup?

Download this file and put it in your Toribash directory to kill the blood
(you should probably right click the link & save as profile.tbs because browsers suck at downloading text files)

Edit it in notepad if there's any other options you want to change on startup, so long as you don't use the leading / at the start of the line it'll work.