I have lifted just one tire with the hi-lift on the sliders quite a few times. No odd angles of the jack and no slipage. Now, would I crawl under the truck, hell no, but I wouldn't do that no matter what jack I was using and where I was lifting from.

If you used Por-15, lifting with the hi-lift is not going to be an issue, but again, the chances of your running your slider along a rock is greater than the chances you will need to use the Hi-Lift.

They will get scratchs, that is what they are there for. If you are that worried about it, you better not leave the pavement...and I don't say that to be rude, but it's the truth. If you wheel, you will get scratches, dings and dents. It's part of the game. It's the reason you buy things such as sliders and skid plates.