Even though it is not recommended to use an air shock, it can be done. The reason we don’t use them much without getting too technical is because the leverage ratio on skibikes is very different than on mountain bikes. In order to keep the shock from bottoming out, the air pressure needs to be higher than it would normally be on a MTB. Not only that, but we must not forget that air volume decreases with altitude and cold temperature (the colder it is, the more air pressure you need). It may not be possible to get enough air pressure in the shock to keep it from bottoming out. Can it be done? Yes, usually with the addition of volume spacers (you will have to look that one up).
Even though it can be done, we do want to advise that you run a higher risk of damaging the shock since it will be easier to bottom out.