If weather is going to be excessively hot and depending on size of your black tank capacity you may want to as I say to husband "prime" the toilet before leaving. For us that means a small amount of water in the actual tank and a teeny bit of dawn detergent. The dawn we find helps keep the sensors cleaned as we don't dump until our tank is very close to FULL up. Some other folks prefer Happy Camper or just a deodoriser.
Just saying as a tip to have a pleasant trip. Bottom line with black tanks to keep smell down and avoid paper pyramids, is plenty of water. Ours is 17 years of extended trips and never an issue yet (touch wood!).