We do not recommend using HeadPLUS v2 PRO with the SliderPLUS v5 PRO Long because the SliderPLUS v5 PRO Long's carrying capacity is 20lb (9kg) while attached to a tripod, and the HeadPLUS v2 PRO itself is around 7lb (3.17kg).
With this in mind, the HeadPLUS v2 PRO's 20lb (9kg) carrying capacity cannot be fully taken advantage of when attached to the SliderPLUS v5 PRO Long.