How to Finance this deal?

[Bryan Wilson]

So, I've been living in my SFH for about 8 years and was fortunate enough to land a price point that has since built up approximately 80-100k in equity depending on the comps. I have a highly desirable property on a lake that I am purchasing from my Grandma. We want to build our next home on this land and the all-in cost would be about $300k. I currently owe $143K on my current home that has the equity built up in it. We can not qualify for a construction loan and build without selling the property it would seem.

Any outside the box suggestions to how I can keep my current property as a rental property?  I'm not opposed to selling the property, but want to keep it for my rental portfolio.  

I'm open to renting it out and renting myself to create a seasoning period if need be, but would hope for other options.  The land does not need to be purchased yet as our contract states that we have right of first refusal and currently my Grandma holds the property and pays the taxes until we decide to purchase or she dies in which we would have to purchase at that time.  

The last option we have is we do qualify to buy the land and can slowly pay it down and stay in our current property as well and pay it off.  My wife will be returning to the work force soon after having had a baby and deciding to have her stay home for a year to take care of him.  A lot of this can solve itself with her income coming back in, but was just curious if we could work it without her going back just yet.