Hi,
I'm not sure how that would work. You would need to put the purchase on both sides of the outhaul to keep keep the line speed the same on both sides of he outhaul. That would give you even more problems putting enough tension on the line to prevent it from slipping the line tender. Apart from not having enough space on the boom to do this I think.
Regards,
Arno Luijten,
SV Luna,
A54-121