Personally, I don't envision there being nearly this much high ground, but it's not a thing I've explicitly discussed with
@OliWhail or
@Velorien, so maybe they disagree. This is why, when you originally had no design for the fort, I created a square platform with curtain walls -- even that was stretching the chakra supply, but it was vaguely plausible. What you're trying to do now, building what is essentially a medieval European hill fort, seems pretty unlikely but I'm trying to roll with it. Again, haven't had a chance to discuss with the others.
A third thing we need to discuss is how the other genin are going to react. The idea of turtling up like this is antithetical to every tactical plan taught in every ninja school in the EN, so they may not want to follow you in. (For the record: the reason it's antithetical is because ninja abilities vary so wildly, and there are so many uncommon jutsu, that you can never anticipate all the attacks and most defenses can be trivially bypassed.)