A mini-tub without the spring relocation? Wouldn't buy you much. The springs and frame rails are in the same place on all of these cars, it's the outer wheel well and width of the quarters that's different. I know that on my Duster the inner well is slightly more limiting than the springs with the offset hangers, but, it's not enough to allow for a wider tire. I only have about 3/8" to the springs with my 295's, and the addition of a rear sway bar kept the tires from rubbing on the inner wells. Moving the inner wells to the frame like with a mini-tub would give the 295's some space, but, you couldn't go any wider because of the spring clearance.
Pretty much no point in doing a mini-tub without the 3" relocation, just like there's no point in doing the 3" relocation without the mini-tub.