I take Scotch brand double side tape and stick it to the chassis under the battery and then use the strapping tape like I always have. Not had a lipo come out or even move in my car yet. And I have hit some stuff pretty hard.
in my other lipo cars, I have massive strips of velcro for a battery straps plus velcro on both the bottom of the chassis and the battery itself. It's been though a few warp speed cartwheels and it didn't even budge.