I use a piece of 1" white in the front and back of my thumbhole. Along with this, I put a couple of pieces of Brunswick protective tape on my thumb. The tape on my thumb helps avoid blistering, now that my drilling is spot on.
If you grip the ball excessively, or have the wrong thumb pitches, then white in the back will cause you a lot of problems (not insurmountable ones, but still). However, now that I've fully adjusted I couldn't go back, the tape provides extra friction, meaning I barely have to hold the ball at all, and can bowl all day with no blistering...
It's not for everyone, but with a little patience, it can work, and work well...
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Reporting from England