insert a character after each character
I'm reading and I see ipX, which seems kind of what I want, but I want to be able to tell it to do it after every character. Do I just need to write the rule out like 31 times? An example of what I'm looking for is like if I want to put a 1 after every character, so it checks: 

Do I just need to do i01, i11, i21, i31, i41, etc, all the way up to some length that I choose?
Yep, that's pretty much the way to do it. Use hashcat's "--stdout" feature to test to see if it's working like you're expecting.
I was about to ask the same thing. Glad I came across this thread.