You do indeed run these risks. Subrogation is always a possibility unless there is a waiver of subrogation agains th the pilot in the policy. How do you find out? You have to see the policy. Wehn you hire an aircraft or even work as an instructor you will probably only see the insurance certificate which does not give these details. So you have to ask. If the information is not easily forthcoming then you should act as a prudent uninsured. Either get your own cover or make damn sur you do not do anything to breach any of the rules. If in doubt ask me... As well as being an instructor I specialise in aviation law...