hilda, i did a 6 room, 7 hallway very very decorated maze, each part was a transition to the next area and i did halls that you had to duck under, or had noodles hanging down to get through things like that..........heres what i see....have them go up it not down it, cause kids tend to run leaving, going up they wont and will go slower waiting for the scare so will be safer..oh yes you can make your cave with pvc, yes yes yes...i can draw you a pattern right now for that...you do not have to glue it either.........use the thicker pipe, try not to make your spans more than 6 feet if you go 7 feet high, (my maze walls i did with pvc in 3//6/9 feet x7 ft high sections and then i coverd each every year and broke it back down to a pick of sticks..lol) duck tape your joints so you can undo them when you take it down, when you do the top also do the bottom for support....you can zip tie them or wire the together buy electric fence wire...........you can set this up alittle bit away from your ramp and decorate the ground as a scenes, make part a transition like pitch dark, into lights, your scene, to the porch as your finish. just that little walk can tell a big story however you want to decorate it....over the top (i would enclose that also) you can hang curtains or things they have to walk through etc etc etc....maybe refresh your safety treads on the ramp so they are new and rougher so someone wont slip, put a warning sign at the beginning with your "rules" ex, High grade, walk with caution, use hand rails, beware of the cave dwellers etc.. ............if it rains and thats the problem with outdoor set ups have a plan b in place, only way to avoid that is have a tent to cover all this to keep it dry...i dealt with weather anxiety every year till i bought a big *** tent to cover the whole maze i did. this sounds great fun!!