Thank you, I'm trying it out right now!
I'll keep you informed 
edit1 : It worked for the minimization (it's now at 3.76GB) I'm writing it to the sd card with Win32 Disk Imager (I used arch to use your bash script) I'll keep you posted if my BPI boot! To boot it up I just have to press the power button for a few seconds right? I don't have to do anything else?
edit2: Alright so now my BPI is booting with 3 led (no more only red light as with other imgs) but it stop after like 10 seconds