how do you structure 100% owner financing?

Simply do a land contract where you act as the bank. Having said that, with a 17 cap, you may not want to sell.

If you are actually going to transfer title to her and let her make mortgage payments to you, I would strongly suggest that you have an attorney prepare a loan document that gets recorded so that she is not able to borrow other money against your property and jeapordize your collateral position. Another way to structure would be to prepare a lease-purchase agreement where you continue to hold title to the property and you base the rental amount on an amortization schedule for a loan equal to the purchase price of the property (typically I use an interest rate of 2% higher than the best available rate). At some point in the lease she should have the option to purchase the building from you by obtaining conventional financing, and you can credit a portion of her lease payments to the purchase price, based on the "balance" on the amortization schedule for whichever month she purchases the building. This way you have not transferred title to the property and if she decides not to buy or defaults, you still have your property. I would also suggest you consult your tax professional to make sure that your agreement does not create any negative tax consequence until you actually transfer title.

If you are actually getting a 17% cap what would you be charging on the note? If it is less than 17% (assuming you calculated the cap right) why would you take any less? Some states have usury laws you need to watch out for.
Another thing to keep in mind is that a 17% cap is sky high. If cap rates in your area for this type of NNN are at 8% it would mean that if you sell to your tenant at 17% you have grossly underpriced your property. Did you include debt in your cap calculation? If you did then you have calculated cap wrong. Cap does not include debt service. Also keep in mind that your cap and a buyers cap will be quite different especially if prices in your area have risen substantially since you acquired the property.
What you need to do is an IRR analysis for both you and a potential sale. I can do that for you if you like?
My e-mail is: paulsylvester@remax.net
Phone: 800 554-7362 ext. 208

You'd be crazy to sell if you are actually getting a 17% cap rate. You'd loose money in the deal.
If you want to sell no matter what, I'd recommend you speak with a local escrow company that can set up a long term escrow account for the seller financing. There usually is some nominal charge, but they can handle the paperwork and the collections going forward.

Selling? With a 17 CAP? Why?

Regardless of the CAP rate, without a down-payment, banks, in their "infinite" wisdom will not touch a loan. Seller second does not mean anything, either.
Your only options are to "be the bank" or find someone who is interested in being the bank.
If you choose to service the loan yourself, a company like Virgin Money http://www.virginmoneyus.com/RealEstateLoans/tabid/55/Default.aspx can handle the paperwork for you.
If the property is indeed at 17 CAP, and your buyer has decent credit, then you may want to contact one of the private note purchasers, such as, http://www.thenotebuyer.com/ , http://www.bostonnote.com/, etc. They will help you structure the loan and cash you out at the closing.
Another option would be to contact your area real estate investment clubs http://www.nationalreia.com/clubportal/795files/directory.cfm?clubID=795&pubmenuoptID=11912 to see if any of the members would be able to structure the deal while benefit decently from the transaction.
Best of Success!
Lee