Dies and chambers vary in headspace length and it sounds like you have a long chamber or a short die, or both. I have two sets of competition shell holders and normally only have to use a plus +.002 or +.004 competition shell holder.
The only thing I can think of is to use feeler gauges to adjust the die upward. Meaning place the desired thickness feeler gauge on top of the shell holder and adjust the die downward until it contacts the feeler gauge. I used the feeler gauge method when I first started reloading but it meant moving the lock ring with every adjustment.
NOTE, Whidden custom die website tells you to not screw their dies down to contact the presses normal shell holder because they make their dies shorter than other die makers. Meaning there is always a air gap between their dies and the shell holder. I use the Redding competition shell holders because my old 1973 Rockchucker press has slop in the linkage. And with cam over and using the Redding shell holders the slop is eliminated and I get more uniform shoulder bump using the Redding shell holders.
Bottom line, if you do not have a old worn press with slop in the linkage you should be able to have uniform shoulder bump with a air gap between the die and shell holder. Before getting the Redding competition shell holders I used a die shim kit with different thickness shim/washers to raise the die that created a air gap below the die.
SINCLAIR INTERNATIONAL - RELOADING DIE SHIM KITS
https://www.brownells.com/reloading/reloading-dies/replacement-parts-upgrades/reloading-die-shim-kits-prod33711.aspx
The Sinclair Reloading Die Shim Kits allows you to make fine adjustments to your reloading dies quickly and easily while still being able to return to your original setting. Each shim is notched for easy size identification. Just set your die using one of the middle thickness shims, adjustments can be made easily by changing shims to increase or decrease die depth without changing the stem setting. A great upgrade to non-micrometer adjustable dies 7/8-14 Shim Kit includes 7 Shims of varying thickness and are best used with Sizing Dies
Below the Whidden die warning.
WARNING
Failure to adhere with below warning could result in damaged and unsafe brass!
The Whidden Gunworks Sizer Die is engineered with a shorter overall length (OAL) compared to other manufactures of sizer dies. This means you can set the shoulder back further if
desired based on your specific application. This die is not intended to be used while bottomed out or screwed flush with the shell plate. Doing so will result in the shoulder being set
back too far, possibly rendering the casing unusable. During initial setup screw the die flush with the shell plate
then back off 1-1 1⁄2 turns, NOTE: Each full turn of the Sizer is approx.
.071” so it does not have to be turned very far to make a noticeable adjustment..