My thoughts, its your bike...do what you like.
Ride what you own...own what you ride.
My only real concerns deal with comfort and riding position, not for yourself but for your dad, if he is the intended rider. It looks like the riders legs would be "crunched up" and cramped.
The extra seat thickness with the shown handle bars may make manuveering the bike difficult.
Also if he is short, the extra seat thickness make him less stable if the bike is stopped on an unlevel area, or start to tip over.
just some thoughts,
Lee