It sounds like you might a perfect candidate for Fidelity's Income Replacement Funds. These funds provide gap income and pay back all principle within a certain time frame. Take a look at Income Replacement Fund 2022 or 2024

http://personal.fidelity.com/products/funds/mutual_funds_overview.shtml.cvsr?refhp=pr 

Scroll down and try the calculator. Then scroll down some more and click on - 

'Research All Fidelity Income Replacement Funds.'

Paul