Jackable rock slider sills
Please be careful when using a Hi-Lift (or similar jack. They are inherently unstable in use and can easily come detached allowing the vehicle to fall. In fact, one use of the hi-lift jack is just that - to raise the front (or rear) up clear of ruts and then allow it to fall in an arc out side of the ruts.
Yes, use a Hi-Lift to raise the vehicle, but then lower it onto axle stands before working on it.
Also, bear in mind that you'll have to jack the vehicle to quite some height before a wheel will leave the ground, that's' why the standard jack is designed to raise the axle.
Lawrence