Thanks, @Elothan . Would I not want to use the 4-into-1 into the right printhead then? Right now, I have the upper buffer and extra inlet feeding an internal 4-into-1, which then feeds the right printhead. If that would work it would be ideal–for me to disconnect the PTFE at the printhead I need to remove the top cover anyway (due to my dexterity level…)
You need to disconnect it at the printhead to relieve the pressure that makes the TPU assist module work. I am not sure if disconnecting it anywhere before will be enough.
OK, thanks, I’ll probably just stay with the overhead HT for now… 
I get the impression that TPU is still kind of an afterthought workflow…