Water closet venting

Hey plumbers and plumbers

Fairly experienced plumber here. I have an unusual scenario where I need to drop a toilet down, over, and down again to keep it both inside a wall, and the vent low enough to not ruin floor joists.

As per the OBC codebook, I cant find anything that says it isnt permitted to use a fitted 90 over to a 90 down, and then pull a back vent off the second drop. I am within 1m vertically, 3m horizontally, and do not exceed 225° before vent.

Clearly not the optimal set up, Let me hear your thoughts.

FYI: it does work fine, no other traps are pulled. I am curious about code compliance.