It's not a big deal. You can with a little effort push the crank arms on far enough to engage the stopper plate with your own hands. At least I have been able too.

The only purpose of the fancy named pre-load adjustment tool is to get the crank arms on the spindle at the proper depth to let the stopper plate engage the notch in the spindle.

There are all sorts of tools listed in the Shimano documents for the components on my bike. I frequently get by without most of them. Why does this one upset you so much?