your idea is crazy but not bad if you have very big capital to survive all the market price. you can do it with small lot keeping a lot of free margin to move minimum 1000 pips in any direction. i think then you can make a lot of profit in time. your profit will not come every time but when the price is change then you got big profit at a time. first you can try this in demo account then you can see the benefit and drawback of the strategy. i think keeping only buy or sell is no possible you have to keep both and wait to get profit.