Ok to leave the black water tank 1/2 full while in storage?

Not something I would do, but depends somewhat if half full is mostly liquid, or lots of solid waste. I doubt the blue packets would do much after 2 months in the heat. I do try to always keep some liquid in my black tank, even in Winter storage, rather than let it dry up. After a good rinsing, I'll add quality anti-freeze, that won't evaporate, and helps lube the valve seal.

Jerry