I haven't tried all the chassis, but I had difficult times balancing the Vudoo 18" Kukri in -
MDT ACC
MPA BA Comp
Manners PRS1
Manners PRS-TCS
The ACC, I could if I put on all 5 external pairs, and all 5 internal pairs.
Manners PRS1 I could do it if I threw on a weighted arca rail fully loaded, and a bipod.
MPA BA Comp, didn't have enough weights to get it to work.
Manners PRS-TCS, had all 7 weights in the weighted arca rail, and remove all rear weights, and no luck. Possibly if I got the steel arca rail instead of the default aluminum one. And I needed to throw a bipod on the front.
Some possibilities where 18" Kukri might balance.
KRG Xray with the full arca aluminum foreend that adds 1.5 lbs + the foreend weight.
XLR I think has a pretty light rear.
Maybe the Foundations with weights?