Financing for rental builds after cash purchase of residence/land

[Tanya Manning]

Hello BP members. I am hoping for some thoughts on the best way to move forward as we move from our current home to our new, and final,  home.  Our home has recently sold and we are under contract to cash purchase an un-zoned lakefront primary residence with 8 acres, of which 5 acres are flat and cleared. We want to get financing after closing to build a 36x36 woodshop and a 36x36 barn with vacation rentals, maybe long term rentals, built above them, either as one building with a duplex on top or 2 separate buildings each with a rental on top. 

My question is what options should I be looking into to get the most out of this situation? Although we have owned a SFH rental for 3 decades in Deland Fl that cash flows about $850/month it wasn't until getting addicted to the BP podcast I started to realize I want to do more. I know there are many creative ways to finance and since I am new to the real estate investment mentality I am hoping to get some much appreciated guidance on the best way to make this purchase more than just our place to live. If I were in my 20s or 30s house hacking and having less residence and more investments would be a clear choice. (It would have been nice to know then what I am learning now.) But since we are older investors and really don't want to move anymore we don't want to get a residence that isn't where we want to be for our forever home, thus the lakefront acreage.

We would be putting in about $700,000 cash to purchase, and looking to finance out about $300,000-$400,000 to do repairs and the improvements I mentioned. We are semi-retired with my husband working from home. Should we look at a heloc on this property or the Deland rental which has a guesstimated value of about $150,000? Subdivide the land (we can subdivide up to 7 lots with a minimum lot size of .57 acres) and then try for a construction loan per lot? Maybe try to get zoning for RV lots and put in the infrastructure for water, waste and power? Something to mention is that the flat acreage does NOT have a view of the lake, or is direct lake frontage since the land dips down to the lake where the residence is. However we can offer the use of a separate dock while they are staying there. 

We are crunching the numbers before due diligence is over and my hope is someone more in tune with this type of activity from this forum can help. Thanks in advance.