The advice I spoke of about practice holds true with the Viper. The Gr. 4 Mustang has similar understeer feeling. This is one of the times I also mention using brake bias. Moving the bias back (+1/2) helps by not throwing so much inertia onto the front tires. It will help the car feel stable if braking in a straight line, maybe a bit loose if you attempt to trailbrake. Also, when exiting a higher speed corner, learn to modulate the throttle. Might need to apply & release a few times to help the front tires to grip if you feel it wash out.
Trust me, if I can win in it, anybody can. You may be right that it isn't the best to qualify with, but it's not bad in race.