I have recently purchased the Royal Class edition of Eduard's 1/48 Bf109G. So I decided to try my alternative method of reducing the fuselage length. I am happy to report it worked better than my original method see photos & judge for yourselves.

The 3 stages shown together.

Lines show cuts to be made. I used a compass set to 1.5mm to scribe a line parallel to the first panel line - the area to be removed.

The fuselage in 3 parts - cut using RB Productions Pico Saws( a very good product).

Fuselage rejoined without using any plasticard strengtheners behind the cut. A little filler required, panel line rescribed & it may be possible to re-instate the rivets, with the appropriate tool.
I hope you find this method a lot easier than just cutting the fuselage into 2 pieces.
Gaston, thank you for your comments and yes the cockpit opening on the Eduard is 13mm.
I will again praise this kit as being the best Bf109 at present available despite the dimensional faults, which it would appear does not concern a lot of modellers.
I now have 2 spare fuselages, thanks to the Royal Class, maybe I'll try grafting them onto a couple of my Hasegawa 109s!!!!!!!
Andy