Shorter cranks on Double Vision

I did a Google search to see if any new pertinent information had come to
light lately. All that popped up were posts of mine, expounding the
gloriousness of shorter cranks. I am at least a year into using shorter
cranks (165's) and I positively have no knee pain on my single bike.
The tandem (Double Vision) has 175's and my knee always hurts when we ride
it.
Any new ideas on shortening cranks on the DV? I called Vision and Ricky
Comar said it would cost about $15,000. Machining, R& D, prototypes, etc.
(I have heard that Ricky Comar is not at Vision anymore...)
Perry
bentcajungirl
down to just a
Double Vision
New R-40
Husband's R-44
and still the El Camino.