Free Margin - Hypothetical Scenario for this market

Ok so this hypothetical scenario isn't hypothetical for me, my parents are well off and have offered to loan me any amount of money up 100% of what my current portfolio is worth under the stipulation I pay it back within 10 years and pay off at least 3% of the total borrowed each year at year end. There is no interest at all so it is basically free debt.

What would you all do? On one hand its an amazing deal since my capital is highly limited and I spend an incredible amount of time managing my portfolio and researching investments (I've had to give up great investments for even greater ones) but on the other hand the market is so high right now I;m terrified to be 200% invested in this market with these high valuations.

Any advice? What would you guys do? Remember we are assuming very limited capital. The transaction costs literally limit me to owning 10 or so stocks before they begin to represent a substantial cost (as a %) of each transaction. In other words when I buy 700 in stock I am automatically 1% down from the 7 dollar transaction fee (that's hypothetical its actually 5 dollars per buy or sale).