I would like to open long and short position at the same time in Kraken. For example,
0.5 BTC short position with 2x leverage
0.5 BTC long position with 5x leverage
You mean by using (leverage) loan funds and you open / invest every 0.5 btc Bitcoin in short and long term options.
Indeed the trading method against Bitcoin is often used by people through the two paths 'short and long'. If you are able to control the movement of Bitcoin prices per second and hour, no problem, but if you are not good at trading using leverage, your risk is very high, you can be destroyed that way, borrowed funds.
However, if you understand and understand in crypto trading the two methods are good to do, the benefits you get from short-term investments you can cover the long-term leverage, both of which you do depending on your knowledge in the world of trading, analysis, prediction, thoroughness and control.
If my advice to you OP, if you have 1 Btc leverage, you do one thing, which is a long term investment when bitcoin breaks high prices and sells and all assets and leverage are returned, profit from the long term, you can use the 'short and long method, you avoid burdens and problems.