Parking lots –
Even rain can suck. A parking lot has some mathematical gallonage of water run off heading toward your haunt at ground level even if the tent and such hold together fine. I have watched parking lot haunters run to the back to sweep out water that begins to accumulate in back rooms sufficiently high enough to start pushing walls around.
The solutions are, sand bag the upper side of the walls at floor level to divert run off water, raise the whole wall system on bricks or some other added device or don't do it.
For security, we are indoors and even I can't get in with out calling someone but, I have always thought any sensitive equipment and all the tools would be in a van or small enclosed trailer that can be pulled with a pick up truck and it goes home when the place is not in operation. You can go nuts with stereo type connectors to be like quick disconnects.
I also thought that there are usually lots of sensors to run lights, sound and props, why not have a second circuit for off time that just lets someone know there is someone wandering the halls in sector B?
For the most part, these kind of haunts have very few props, only walls in fear of things being taken and that sucks as far as entertainment goes. On the same token, lots of props and set decorations can be made cheaply and considered expendable or disposable. Sort of like you can tell how good a party it was because they took everything. Alas, no storage expense for those small items.
Another fabulous post from the U.S.Department of Wild Imaginings, now in spectaclar stereo, sponsored by the Adhesives and Sealants Council, suggesting ways to stick things together since the 1800s. Not fabulous in a gay way. Your results may vary. Illinois residents add 8% sales tax. These posts have been made by professional post makers, do not try this type of posting on your own without extensive training, lovely assistants and a trusty clown horn.