In theory I guess that you could try to do so but in reality I would think that any one that is injured as a result of being in or around the pool is going to sue you as the home owner as well as teh tenant.  You are the "deep pocket" and ultimately if the injury was as a result of say slippery type of tiles installed, the finger will point to you.  As for the fence, if this is part of your local ordiances or code I would not leave it to the tenant to install. Please speak with ana ttorney in your area.  Do NOT write this clause yourself.  Require the tenant to have separate insurance and to add you as an additional insured on the policy as well.  Good luck.