I was going to drop in and clarify some points, but...
our friend hopped in and spelled it out in specific details.
You can calibrate input/output paths with raw test tones.
You can set bias with test tones.
You can calibrate the tensions if you like, given a proper spring scale.
For calibrating levels of the head reads & writing to the tape,... is specifically where you're out in the woods without an MRL tape.
I'm not sure if bias adjustment is level sensitive,... but the MRL helps set flux levels and basic EQ, & may play into the bias adjustment. Many analog adjustments interact in the setup process.
Thanx to our friend above for helping flesh out the specific details. My mind was blank, but I'd come back to clarify.
Sorry for the glib answer up top, but many of these products would perform reasonably well right out of the box. However, I'd be more secure going thru the setup of a recorder if I had the MRL on hand.