The lease should be about $800, that;s close enough to market rate rents, IMO. It's a lease in one document.
The other is the Option agreement, at the end of the option period, they need to have 10% or more in the option or paid.
They might pay $6,000 at signing, or
Say they pay $3,000 at signing, they could add to thier account $84 each month or any amount to have the total there when the option is taken, or
They could sign a note for the option price, with interest and you could finance the option price. 182.53 pays 6k in 36 months at 6%.
The arrangements can have endless solutions as to how the get the option price paid over the term.
If they sign a note, the note is "good" as it is given for the option and so long as the note is current, they can take the option as agreed, at any time over the term.
If they don't buy, technically, the note is still good, it's a debt for having given the option, it was the option price and they could have taken the option at any time over the term, so it is still owed. Collection would be as an unsecured debt, well, unless you secured it with some other collateral.
What ever the payment and rent amounts might be, you need to make sure it's affordable, that they can reasonably pay for the deal and that they are able to perform at the end, especially if you finance the option price.
The L/O can be considered an installment agreement, especially financing the option price. When they get to the end, they will get credit paid under the option agreement, 6k on a 60k purchase agreement and will need to finance 54k or 90% and they will have buyers expenses and loan costs.
Your lease can be slightly less than what you might usually get to offset the payments toward the option. In fact, it is financially and legally acceptable to pay lower rents after having paid an option, it's negotiated as to the value of money over the term, but, it needs to be near enough to market so the rents are not seen as a seller concession which reduces the ability to obtain financing.
I really, again, suggest you see your attorney since this is your first time and lean on them! Good luck....