but they're not proper bleeds
Are you the printer? For most bindings with folded and gathered signatures (saddle-stitch, perfect , smythe sewn, etc.) the interior bleed would be removed in the imposition. For bindings where the interior edge is actually trimmed rather than folded, like wire-o, an interior bleed might have to be built manually for pages that don't have crossovers:
Yes, I am the printer dealing with customer supplied PDF files.
Your link appears to answer the question. I will forward the link on to my customers and see what they say, Thank you!