Correct, the 17.5" tires are the tubeless equivalent to 16" tires.
New 17.5" tires are out there, but can be hard to find and expensive.
I did sell a set of seven 17.5" wheels from a 61 ford I had to someone who wanted to go tubeless even considering buying the rims from me, shipping to AZ, and finding the expensive tires, I even had a few other folks waiting in line if the first guy did not take them.
Personally I would not buy or mess with 17.5" tires, but I also have not been in a situation where that was my only tubeless option...
Grigg
