Min test plate length is 7". Using longer material is OK.
Fig 6.21 shows to cut bend samples 1" off center, so the leftover plate at the ends is inconsequential.
However, there's no getting around the visual acceptance criteria of 6.10.1. This criteria applies to the entire weld, excluding only weld tabs.
Look at it this way - A performance test is a way for a Welder to show that he/she knows how to and is capable of completing code compliant production welds. If a Welder did not complete weld joint ends in a compliant manner on a production weld, would that be acceptable?
Tim