Ok, used this method and here are my observations:
You have to wrestle the fuel lines out of the way to get to the ports which necessitates cutting off any zip ties you've secured them with. I also had to disconnect the fuel line clamp on the right side to clear the right port so I could get to it.
Second, although I was initially pretty sure I squashed the balancing crossover hose enough to isolate the two sides, I was never quite sure. Here is a clue I might not have: I was having trouble balancing with the CarbMate so I switched to my basic motorcycle mercury filled cages. As I increased or decreased throttle, one side would lag but eventually even out. It was the "long side", i.e. the side furthest from the clamp.
I did manage to get them balanced. One advantage of this approach is that you can remove the clamp from the crossover tube, when you're done balancing individually, and see immediately how the carbs normally perform.
All in all, I didn't find "Option 3" any more convenient than the other approaches. Given the stuff you have to disturb to get it done, I'm going to stick with Option 2. That way I'm absolutely sure I have isolated the sides and besides it's the same of work.
Here are the fittings I used: