It may seem strange that a tripod needs support, but when loaded with a slider a little help is welcome.
The weight shift of a long slider and a camera setup is more than any single point tripod can cope with. It will flex as weight shifts. The solutions is usually to get two mounting points for the slider by resting one end on the ground or by using two tripods. The two tripods can be difficult to set up, however.
An alternative solution that might save setup time and save carrying weight is using a tripod support arm, or preferably two.
Both Alzo and Konova has their support arms.
The Konova Tripod Stability Arm for Slider cost approx $90 each (free worldwide shipping) and is available directly from Konova (sponsored), or some select eBay shops.
Alzos version is called the Support Brace. The Support Brace is avaible directly from Alzo or one of their retailers, such as Adorama. A full arm cost about $70, and a version without clamp is available for approx. $46.
The construction of these are pretty simple, so a semi DIY solution should be easy to make. It involves putting together a telescoping arm, ball heads and clamps.