1/4 Scale.. Now we are talking !

Its a game of trading off potential issues. For me on a model like this I would rather add nose weight than deal with fuel away from the centre of gravity, and an angled tailpipe. I also like as short a tailpipe as possible. I am no genius when it comes to tailpipe designs, I just know through experience that the shorter tailpipes ( for a given diameter ) have proven to work better/ more efficiently in planes that I have flown.
Many years ago I remember a company called Jet Welt came out with a model called a Jet Provost. They showed it to us at the jet masters in Thailand. The full size has a very short nose and long tail so for the model they put the turbine right forward in the cockpit, with a long pipe... Just so they can reduce nose weight. I saw it fly and it looked awful. Sounded not so nice either. When they came to production the turbine was more in the normal spot and the model needed lots of nose weight, flew great and I owned three of them over the years.
Keep it simple Mirce.
Regards Al