Tri bar fitment on taper handlebars

[JuicyUltimate]

I'm busy setting up my road bike for this year's Iron Man. But I've got a problem to mount my tri bars onto my handlebar that tapers down from the stem. It's using about 70mm of the handlebar to taper down from the stem on each side.

 

My question is, what is the maximum gap between the two tri bars, but to still maintain a good earo position and have an effective pedal stroke?

 

I know to buy a non taper handlebar is probably the best option, but I consider this to be my last option.