Strategy for passing Multiple Parameters into a form

Hello Community!

Entity forms have a nice feature where we can use the OOB interface to specify a Record Source Type; I can pass a parameter into a form by: QueryString, Current Portal User, and  Record Associated to the Current User.

I have a requirement where I have a ReadOnly form. However, I need to pass in TWO (potentially three) parameters into the form in order to get to the right record. Has anyone discovered a way to do this without going the pure extension route?

Any thoughts/suggestions would be appreciated!

Thank you!