Friend Jan shared this link with me. This is a technique for trimming half square triangle units from Little Miss Shabby. Give it a try. It looks to be brilliant. 

Note: Jan tried it and advises to be sure your can "see the stitch line" when you trim. In other words, don't set the ruler right on the stitch line or you will come up a smidgen short.

Thank you to Little Miss Shabby and thank you to Jan for sharing.