Well, We plan to setup a Pi to give him remote control of the box. So I won't do any managing short of a hard power reset if needed.
If he decides not to pay, I have his miner...
I plan to charge a flat fee for power consumption costs. That's a min at a cash value.
I was thinking of having him set his mining payout to coinsplit.io
And just take a percentage, I was thinking 10-15%???
Setting up a Pi for remote access is nice. Takes a lot of the hassle off of you for everyday changes the owner might wish to make. In terms of charging the flat fee, how are you planning to bill the guy for it? Just send him an invoice for $20 every month for the electricity costs? Put it this way - that S5 right now expects to earn 0.01429
BTC a day, which at current BTC prices is $4 a day thereabouts. At 30 days a month, your $20 is already about 16.67% of his mining profits. Adding another 10% to it would mean you're asking him for 26.67% of his mining profits. Again, this is right now. That changes each difficulty change and also changes as BTC prices fluctuate. That's the problem with charging fees in fiat - it results in different percentages of mined BTC being paid to you.
You can certainly simplify things and tell the guy, "look, as of right now, I will charge you a flat 25% of what you mine. This rate will be reviewed weekly and changed as appropriate based upon current value of BTC in fiat and/or how much the miner currently makes based on network difficulty."
