support the wings on either side of the fuse at the center of lift, roughly 1/2 way to the tip. Weigh the fuselage to see how much force is going to be applied at the wing center. If you determine that your plane can take 9G, find some weights adding up to 8 x the fuselage weight and pile it on the fuse a little bit at a time, so that weight of fuse + extra weight = 9 times the fuse weight. If you know how fast your plane is flying relative to it's stall speed in level flight, you can figure the G-load under maximum lift (square factor). I would use 1.0 - 1.5 for Clmax on an airfoil without flaps at low Reynolds number.

2 times stall speed = 4G
3 times stall speed = 9G