Another option, assuming your tray cable is round, is a cable gland. Normally a real metal (brass / nickel finish) one that big will be ~$50, but a cheap nylon one can be quite inexpensive. Even in that size.
I looked quickly at Newark.com and found this...
Hard to believe it's $4.32, have no idea how much shipping would be.
Your 1.625" cable is ~ 41mm in diam. And this part (PP002115) lists cable sizes for 34 -> 44 mm.
Fits in a 61 mm hole, which is really close to a 2" NPT knockout (I think). Assuming you have a set of standard Greenlee punches.
Just a thought if the Romex connector does not work.