It can be done, They make a plastic riser that is sold on the net with 7" closet bolts that connects to the existing flange.
I'd prefer a custom built elevation before the plastic, made to conform with the skirt line of the toilet.
Either that or go with a wall hung and set as high as you want, going to cost more to design that application.
I have one customer that has wall hung AS toilets and hopefully they never leak where they hook to the wall.
I'm tall and I have handicap rails to grab onto.