What a lovely big stretch of perfect runway you have. I am SO jealous. Most of my jets wait months for a chance to fly off such a runway. The only ones I fly from the club's grass strip are my O/D JayTee and my Falcon 120 (with fixed gear).

900g is an AWFUL lot of lead to carry!!!
You need a longer nose, and a lighter tail.
I once replaced the 9mm sheet balsa tailplane from a kit with a foam/veneer alternative that weighed HALF as much. Looked better too with a proper airfoil.