Is it feasible and rational to combine the capability of Tails package and Whonix package to improve the anonymity and security of the client? And if so, how one may implement it?
You have first to define what are your anonymity and security needs, and see if either solution can provide it on its own. Both solutions have different goals and different threat models as summarized by whonix maintainer here. The main feature in Tails that Whonix lacks is amnesic capability, which is making your device forgets everything that happens and leaving no trace about what you were doing in Tails. That function can be alleviated to a point by using a full disk encryption under Whonix.
To this day, no one has implemented or developed a tool that combines both Whonix and Tails.