We also get top dollar for the summer months.Surprisingly we rent out alot in the winter spring and fall.There are major fishing tournaments that bring us extra bookings and people who just come up to fish.We have a covered boat slip with a lift where my boat stays unless someone asks to use it.We make improvements every year to make the place nicer. 

That immediately will improve your cash flow, from what I see.

What is one method/technique of lead generation that was rewarding for you last decade and what is one that you will improve upon or develop? 

They were never home, and only improved our property values by the Upkeep n Cleanliness... 

If there is opportunity to improve on both then many people will pay for that potential.

Pay down the mortgage and improve cash flow that way.Happy to introduce you to some lenders if you need them.

Assuming the improvements resulted in $1 of value per each $1 spent, you each now have a basis of $110,000. 

It is ideal (and will really improve your ability to successfully engage contractors) if you can float the construction draws3.

Typically if they are doing okay the business will hold off on major improvements and wait to move to somewhere else better.

A 0% rate can help get the monthly payment down which in turn can help improve cash flow.