Another option we've toyed with is saving to buy our next primary residence in a few years and converting our current home into the long term rental.

Do you have  a While Life policy you can take a loan out, although I’m totally against them.Do you have paid off cars or toys you can hock?

Anyone who's told me about these syndicators, I always think of the old Aesop's fable; the emperor and his new clothes. 

Golf carts are treated like toys because people have vacation brain.Would you provide a car rental for your guests, or leave a car available for them to use?

Just don't want to take on cash out refinances if don't have to.  Yes

Trust me, I've toyed with the idea.Vacant land where it makes sense to build large MFH stock might make sense, but chances are this isn't the land we're talking about here.The reality is most vacant land in Detroit is being repurposed for parks, the Joe Luis Greenway, solar farms, neighborhood gardens, etc.Beyond that, let's say you plan to hold long enough for SFH prices to get high enough where it does make sense to build. 

For example. 70%/30% up to $X in sales, then 75%/35% up to $Y in sales.

I didn't like the idea at first but after the tiring search with no good targets at sight, I am beginning to toy with that idea. 

But we've got a lot of acreage & a whole bunch of kids so we need to store a lot of toys......ATV's, dirt bikes etc...

I have toyed around with the idea of buying raw/vacant land, and running the site planning thru my firm, then selling that shovel ready land for a profit.