I'd imagine they are very hard to change considering the locking mechanism is electronic. But if there was a suitable replacement that complimented the body lines I'd be interested too. I doubt any aftermarket companies have started to tackle this job. Maybe in a few years when the market is more saturated in used mustangs we will see more things like this coming out, but don't hold your breathe is my opinion.
The rear section pops off but the handle itself has a very difficult removal process. Actually, the removal is easy but the reassembly is difficult.
When you pop the rear piece off and pull the handle out there is a nut you have to turn to "unlock" the handle. To remove it you have to pull out and to the rear of the car. It's a pain because if you move the nut after ward you will never get the handle back in the groove it fits in.
When my car was wrapped, they spent an entire day following instructions straight from the Ford Service handbook that a friend emailed over. They ended up not being able to get it, despite following the instructions. I took it to the dealership and they said it's very easy if you do the removal process correctly.