You can make up a set of chocs that have a hole in the side and through it place a large wide cable tie and piece of cloth on the ali rim and secure them to the wheel. This will prevent them slipping. A large lump of wide joist made into a triangle slope or a metal one similar to the one in the spare kit. I have blocks of different sizes that I use. I trust wood on metal and it is more stable than axle stands. a piece of cardboard placed in the saddle of the axle stand can stop it slipping, I had a set that were dipped in molten rubber, but these were too good and someone else thought the same. I haven't seen anything like them around.