Getting equity out of rental homes built on leased land

[Molly Morlino]

In 2017 we built two rental homes on land that my parents own (they have 5 other rentals on this property).  It's 12.8 acres outside the city limits of Kyle, TX (if that matters).  We lease the land at 5% of the rental amount (so $120/mo for both houses) plus $20/mo *per house* for water and trash.  We do have a 99 year lease with my parents.  All of this is really just for the legalities of their will.

Anyway... we built these with cash and do not owe anything.  We are hoping to use them as collateral OR cash equity when we go on to our next investment (RV and boat storage).  Does anyone have any ideas or tips or experience on how we can do this with leased land?

We would like to build more in the near future it's not the best ROI (33% per year vs 45% per year for RV and boat storage) - but to build these is considerable less money (about $35k per house) vs RV and boat storage ($1.5m for the land, development, etc)

So IF we can get equity or use them as collateral towards the storage investment then super... but if not, then is there any point in building them right now?