abra, I'm the one with the Tow fish/cam.
Vis is not a problem in clear water 25 feet to unlimited vis. In less than 5 feet vis it can be tricky. Flood or IR light helps in deep,dark,clear water but is horrid in muddy or slit filled water(offsetting the light may help).
The tow fish/cam was intended to give a quick look at a side scan target without recovering the ss tow fish, re-rig for a drop cam, reacquire the target. recover drop cam, re rig for side scan. Have a 2 in 1 unit. Chop power,look,access and continue the mission.
Water depth makes no difference at all.
For the neat target I use a Seamor ROV with 3 color low light, IR cam's,Interphase Forward Scan,Humminbird side scan.
All data is feed into 5 hp laptops then to multichannel VHS recorder for storage and review.
My latest Humminbird side scan tow fish has Siamese CAT8 cable.
Will post some shots/pix as soon as I record from VHS to internet file.
Roddy