Well, if you power brake to get the wheels spinning smoothly before you really let loose... that will work too!

(set up a sprayer system using the windshield washer pump that will spray just in front of the rear tires instead of the windshield! That will get you spinning! Lol...)

How old are your springs in the rear? I hope to add a Slide-A-Link set up from Comp Engineering:
http://store1.yimg.com/I/hm-performance_1843_58639871

They look much better, and are less noticeable than the traditional style Traction Bars. But if neither are acceptable, the only thing I can think of is to change the spring rate in the rear, and change the shocks... and as others have mentioned weight distribution etc...

Hope you come up with a good compromise!

Brett - 56 Drop Top 455!