Representationalism might be the tendency to state a thought, notice the meta-constraints, describe them, and then keep recursively trying to go higher and higher.
Heidegger, mystics, etc. would be the people who refuse to try and recursively redescribe, but try and focus on the weird nature of getting into the “first” statement in the first place.
Inferentialism is orthogonal to both. I don’t really even think a thought such as “your preconceived notions constrain what you can think” is a central problem in inferentialism. It’s almost like, given that words are a given, how do they relate to one another. It’s not necesarily trying to answer the “prior” space to words, that either Heidegger or Representationalism inevitably try to do & start navel gazing.