Question: Can I configure spinnaker to use more than 1 role when managing services in aws?

Answer: Yes, you can try setting up another aws account (in spinnaker) with creds+role to access ecs and map the ecs provider to that account. If all your resources are actually in the same AWS account, you could try configuring another "account" for aws in spinnaker that uses creds for a user in your main AWs account but only has permissions only for ecs (and other services leveraged by ecs). Refer to the AWS document for more details