I don't think this really exists sorry! In order to have decent leg room, you either need a metal frame, so isofix, or you need a brace on each side, so tethers.
Could you elaborate a bit on your situation/what you need? For example:
What's the age and weight/height of the child?
When you say ERF are you looking to continue rear facing to what age?
When you say "no tether" do you mean top tether, or the Swedish style tethers that go through the seat rails? And if it's the latter, what is the objection?
No isofix is clear :) But is this because it needs to go in a specific, non isofix vehicle, or you're just looking for max vehicle compatibility or some other reason?
Reclining - as in it has a recline position? Or you want the option of multiple recline positions?
Likely the closest thing to what you want is something like Graco Slimfit R129 or Joie Stages or Graco Extend R129. But the leg room in these seats is not particularly great.