Hide standard elements

Hi,

I've built a bunch of custom epiforms elements and I'd like to display only these elements when the user presses "create new form element". The standard functionality always shows the "standard elements" as well, not only my custom ones. I dont want my users to be able to access these, so im looking for a way to hide them. 

I've tried doing this by css but the ID isnt unique for the surrounding div (i.e "dijit__KeyNavContainer_3"). Is there a way of doing this that im missing? Injecting javascript sounds like a bad solution to this problem.

Thanks alot!