I would recheck with the leasing company, ordinarily the leasing company is just a broker/middle man and the registered owner of said car is under A N Other company name
Seek written confirmation that a towbar can be fitted, which requires a unseen bumper cut (towbar specific varies the extent of bumper cutting) you will receive written notification that it’s allowable ( make sure you keep this) as long as, on return of vehicle you leave the towbar otherwise return to as received condition (which would result in replacing the rear apron and installing original rear frame)
In regards to the kick sensor for comfort opening of rear tailgate/boot, this is repositioned higher up the bumper and still fully functional
Sadly, I state sadly as I only use my towbar for a cycle carrier and once mounted it’s all too easy to swipe the sensor resulting in boot opening, my work around is to run engine (or open boot) when I mount and demount bikes.
Ps
I have a tow trust detachable bar - smallest unseen bumper cut