With Dazzle & UPS Worldship you can customize the labels... Like to see this on the shipment labels as well. We have used to put our logos as well as create shipment tags (available on the standard UPS 4x6+2" tag labels) that we use for shipment info. I like to keep copy on invoices of the shipment, tracking info, and shipment cost... yes its available in the logs, but we want the proof of shipment on a label for your physical records... thus nice to customize labels...
Please support the standard UPS 4x8 (4x6+2in tag) [UPS label #0177400801]... you say 4x8 is only supported by USPS but even that does not utilize the 4x8..
Great news! You can now customize your labels a bit more. Although logos are not yet a customization option, our new templates allow for more information as seen here: How to: Customize USPS domestic shipping labels