Thanks for sharing your solution Scott. It is good to have another option to make this work.
That being said, I found another solution, but never came back to update this post.
I few years ago I tried defining one of the trays with a slightly smaller paper size, like 8.4 x 11. This solution didn’t work in an old HP 4000 TN printer, but it works perfectly in a newer HP M605.
After defining the custom tray size, all you have to do is print your form specifying the modified size. It then automatically picks the correct alternative tray, like this:
printtopdf "","Printer","","Height",11,"Width",8.4
Unfortunately, this solution depends on the capabilities of your printer.