I'm sure any additional option like this
can be retrofited.
But this will definitely set yu back much money. Many parts will have to be purchased including the liftgate panel , headliner in addition to the motor and other electrics...the power button on the tailgate. etc.
Have yu actually seen the power liftgate and operated it? Do so first at a Dealer and yu will notice more of what I mean. This is not meant to be a Dealer accessory.
I will say it may cost upwards of $1K in parts alone. Add labor if yu are not doing the install and it is just cost prohibitive. I doubt yu will even find a Dealer to do this work.
If it was that important...it shouldn't have been an oversight at the time of purchase.
The
PB option appears to be available only with a few option packages. (not by itself).
The
Leather package(
least expensive package with
PB option) would have included this power tailgate option at $2,555.
Good luck.
LT