Long term portfolio on margin experiment a bad idea?

So i was thinking today on how i could take advantage of margintrading without taking a big risk,

The idea i came up with is this,

Take a small part of my total portfolio and make a separate portfolio on poloniex margin,
so for example a normal portfolio would be 1000$, i added those funds to my margin trading account and bought it back on margin for a total value of 1500$,
basicaly increasing those holdings with 50%

for my margin account to be whiped out a price drop of 66% would be needed. (if my minimal calculation is correct )
but in case of a price increase i will get 50% more profits,

so for this to work i am assuming that a pricedrop of 66% will never happen (when buying on a dip)
and an increase in price longterm is almost certain.

portfolio
20% Btc
20% Eth
20% Ltc
20% Dash
20% Xmr

good idea, bad idea?
any other ideas on how to use margin to your advantage without taking a big risk?

Would love your feedback!