During instrument flight training it is common for an instructor to induce vertigo in the student. This may involve waiting until the student is very task loaded and in turbulence already, possibly in a maneuver of some sort (holding pattern for an approach perhaps) and then ask them to pick up approach plates off the cockpit floor (simulating dropped approach plates). This requires fairly rapid bending and twisting head movements to accomplish and will usually induce vertigo. The student is then faced with the challenge of flying the remainder of the approach while dealing with vertigo with only reference to the instruments.
As you noted a diver does have some "instruments" - mostly your own bubbles rising to the surface, and once you get on the bottom the improved visual references help stop it.
My thoughts are that:
1. Your original plan to scooter back up the slope of the bottom to shallower water made a lot of sense in terms of avoiding having to deco in mid water and in terms of covering your bets with terrain navigation and compass navigation as opposed to just compass navigation. It is also a very sound plan in terms of your known history of vertigo issues in mid water. it also makes sense in terms of ensuring a slow ascent. My suggestion is to lay that out as "THE" plan next time you do that or a similar dive.
2. Scootering in low viz in mid water is problematic, but don't forget there are other options. Just because you have two scooters on the dive, does not mean you have to use both of them. You can clip your scooter off, grab his butt D-ring and have one scooter tow both of you together, just like you would in an OOA situation where you absolutely positively need to stay together. Driving or riding, you could maintain a steady head position and, if being towed, could even close your eyes. If the viz is bad and you are not in an enviroment that will tend to keep you together one behind the other, this is probably a far better plan than trying to scooter independently. It is also a great opportunity to practice a gas share on your scooters.
You also have the option of just shooting a bag, ascending up the line in midwater using the line for visual reference, then recovering the bag at the end of the deco and scootering back in on the surface or just under the surface.
