You could get away with not having your trigger bulk ready if you set the batch size of the upload to 1. I wouldn't recommend it though, the processing will be slow. Also, at some point, if more than 1 record is ever processed by your trigger, not having it designed for bulk processing could lead not only to hitting governor limits but the logic may not process as you expect it to.
Ben,
You could get away with not having your trigger bulk ready if you set the batch size of the upload to 1. I wouldn't recommend it though, the processing will be slow. Also, at some point, if more than 1 record is ever processed by your trigger, not having it designed for bulk processing could lead not only to hitting governor limits but the logic may not process as you expect it to.
Jessie