Perfect aim is not the question. If you are over 6 feet tall, and drink lots due to sports or other reasons, you cannot prevent splash-back. Center bowl is a non-starter. Perhaps if you stand off center and nail the near side steep bowl angle perfectly you can reduce the negative effects. However, this maneuver is tricky as volume and therefore arc and angle change throughout the process. It also increases risk of bowl edge contamination.

Or perhaps urethra diameter is to blame. In any case, if you are 6 foot or taller and don't have this problem, please share your secrets because I am convinced it is not possible.