Expose parameters for 'delay' and 'max-attempts'

I'm trying to migrate to the unified cli, and to use waiters instead of polling loops, but the conversion-task-completed waiter consistently times out in us-east-1 for my 12GB disk.

It reports
Waiter ConversionTaskCompleted failed: Max attempts exceeded
but the task does complete successfully. I can write a loop which calls the waiter, but I'd prefer to increase the number of attempts, or reduce their frequency. They appear to be taken from botocore/data/aws/ec2/2014-09-01.waiters.json, which contains the following:

"ConversionTaskCompleted": { "delay": 15, "operation":
"DescribeConversionTasks", "maxAttempts": 40,

I'd like these to be exposed as parameters in the aws cli command, or perhaps for the timeout to be derived from the size of the disk being converted.