However since this is a very large yard their deposit will not cover the amount that would be required to bring the front and back yard to the same condition before they moved in. 

If you pay back all the upfront capital needed to fund the deal, the return becomes infinite after that, so that plays heavy.  

I like the idea of a mix - with a smaller capital contribution being my buy-in and then a second larger amount for funding the first deal being a loan that will get paid back to me over time - over say, 5 years.

I would turn the question back to you  - without a Survey how would you establish the correct placement of the ADU? 

Another item that can run you upwards of $30k if you ended up buying a sink hole that needs tons of fill dirt.

You could get a DSCR closed end second on your rental property but not a HELOC. 

I would rather spend some front end money now and do a relocation, then be able to use simple side-by-side units than to be forced into stackables or all-in-ones.

I've held several different jobs just to make ends meet until this year.

Assuming all other things are equal, the quadplex of 1/1s is going to set the floor value and the appraiser will make line item adjustments on value to back into their opinion of the value of your property.

It all comes back to Landlord who pays the full bill, so it's really not insurance at all.