I was not aware of the PB1xx termination issue. I have mounted a 180 as a SCSI Disk on a 1400 without issue.
Why would you need two switchable adapters? No, rephrase that: you don't need two switchable adapters, only one.
You can even find them built into cables (HDI-50 to normal SCSI 25 or 50). I have one - that, a gender changer/terminator, and an ordinary Powerbook SCSI adapter was all that was required. Three items - not quite the intimidating kludgemonster you imply. I used to take that and my 1400 with me to service friend's 'books.
But you're not asking the 170 to go into SCSI Disk Mode - just to boot normally.