Another plan using forwards.

Get 20 coins
Buy close to 40 forwards.
When bitcoin appreciates, you get the apprecition for 60 coins, not 20, the gain is transformed to coins.
On a doubling in value, sell a percentage of the gain, accumulating the rest.

You can spend as you go, and still have more coins in the future.

This plan resemles rpietilas SSS.

NB. risk of loss of coins. Works only while bitcoin appreciates at large.