Keep in mind what state you are in and that Angelo may not be licensened there, however he could give some ideas on your note. But, I would not be paying anyone other than YOUR attorney. Real estate is local! Concepts can be adapted, specific terms should meet what is customary in your area. Customizing a note or deed of trust needs some local input.
There is no benefit to a blanket loan, especially for the private lender if they knew more about their options. You still need to file the lien on each property, so you don't really save anything on filing fees or closing costs.
Selling with a BL will mean a partial release being filed, does your lender know how to do that or will they be going to an attrorney evertime you want to do something? The PR is no big deal, but if an error is made, I have seen the wrong property released, the amount required being more than what it might sell for and insurance claim problems. Each of these aspects needs to be individually addressed with a BL. You don't have these issues with one note on one property.
You will have a high LTV as I understand the deal. As Jon pointed out, in a BL one property may represent 30% of the balance due. If you had staggered the loans as I had suggested, you could refi on property, say for improments being necessary due to damage from a fire (it happens). That 30% of the outstand balance may not be met to release a property when the LTV of the new loan is assessed on that one property. There are issues with releases.
The notes and security agreements are identical with the exception of the amount, payment required and the legal description of the collateral.
You will also be placing several properties at risk under events of default that can arise, putting more eggs in one basket. No one plans to default, but it happens. How would this be addressed if you were every to sell one property with a sub-2 or installment transaction?
One other point, a BL will be likely construed as a commercial loan. That's fine for you, but what about any future buyer if you did sell with an installment? Now you are blending two different types of loans and rules to be addressed. Having an individual residential loan could be assumed and easily managed.
And, again, seller financed transactions are considered to be financing the transaction, they are not cash advance loans and therefore are more often, except under certain condiotions, without recourse. Making it as a commercial loan transaction under a BL could change this aspect under your state laws, so any deficiencies are simply added to other amounts owing and deficiencies may be sought.
Don't let the number of properties cloud the issue or complicate the overall scheme of the objective and options available down the road. Keep it simple..