Courier contract rewards for BLT hauling services depend on your chosen route, as well as the cargo's size and value.
To set the collateral, use a service such as Goonpraisal to assess your cargo's value, then adjust for items like BPCs that don't have a market value.
More information can be found on the BRAVE Freight wiki page. If you have any questions, feel free to drop a message in #hauling over on Slack.
Routes may override volume and collateral limits.