Since the owner had no real bookkeeping on the property, we did owner financing.  

We are upgrading our services to have them take over our accounting and book keeping as well.

I don't use NNN leases for residential as the bookkeeping is too consuming but it might violate areas of landlord tenant laws which has it's own peculiarities.

I'm looking to switch over to Widget Bookkeeping and Tax.  

And then there's the issues of property tax, park repair and maintenance, bookkeeping, and about 20 other cost categories.I've been doing this for 25 years and I can guarantee you the expense ratio will be 50% best case on this deal as you have described it.

Use Excel, Stessa, Quickbooks, old fashioned ledger, whatever to do your bookkeeping. 

Many on here will charge a flat rate, not an hourly rate, throughout the year that includes the tax return, monthly/quarterly check-ins, bookkeeping, and ongoing email support. 

I think there are other property management software that does accounting and book keeping, but at least I haven't used one that does scenario analysis like you just described.

I use a property management company and they receive rent at the beginning of the month but don't disburse it to me until a few weeks later.For my bookkeeping would I want to record the rental income when I actually receive it or when the tenant pays the property management company?

That is, not just a "bookkeeper."