Is there a rule of thumb for how to go about securing deals like this?

Search 2% rule for example.

As I said, I've never done this, so is there a "rule of thumb" percentage of vacancy that I should go by?

While there are truly amazing resources available, none of them seem to be really equipped to handle the nuances behind the content without the help and involvement of the community or retailer themselves.This is especially true when dealing with the laws and the rules promulgated by the various state and federal agencies.

40% of the gain is my rule of thumb.

You've got to be either dragging a lot of extra info the main ledger to support sub ledger functions or you're missing details you could use for reporting because youre main ledger can't support all that information.

From my research, it is true in most states unless you give the tenants full disclosure beforehand and have their consent in writing or on the lease rules and initialed.

Currently, I am being told that because my wife is on a part time, temp status without two years history of being with her current employer that we will not be able to qualify for a loan and that this two year rule is a government rule, not a bank rule.

I know a few people that work there, I know they are not fly by night, but I don't know for sure their seasoning rules.  

Check with your employer/benefit plan, some have rules that if its not your primary residence that you need to pay back the loan within 5 years, some plans do not let you make additional payments but allow pay off in full as early as you want, also if you leave your employer anytime before the loan is due, you may have to pay it off or pay a penalty.