Question you say this:

Management fees are 1.5% of the total coins mined before expenses (electricity, repairs)

How much is the expenses, you don't seem to detail that.

So if i calculate this out:

3.5 is fees (pool and managment) then there is electricity repairs etc

If you were to mine 100% of the time, which you won't but i will assume you can.

Weekly you are going to get 18 coins lets assume you are lucky and you are going to get 25 coins (makes it easier on the math too!)

that is 1 LTC a person a week.

Which is at current rates roughly $10 a week (which if i am mistaken this is the highest it has been)

so that would mean 12 weeks (3 months) we would get roi of LTC, that is assuming it doens't go down in price.

If you convert that to BTC it is even worse. Also this isn't including anything about Electricity costs and how much that is because you don't say anything about that.

All that being said you are going to store this in a storage unit! I am sorry, but I think you are underestimating how much heat this puts out and how finicky mining scrypt is. And those calculations are just if you are 100% perfect, you miss a day or a hour or have a card go bad, it just goes down hill.

If you say you are going to get free electircity from a storage unit, guess what it won't happen they will pull your storage unit and just shut down power on it.