Here is a work-around. The idea here is to automatically map every key in the event.detail object to a data element so that you can reference each key in the UI. This is done using a Core > Custom Code Condition with the following javascript:
In any action (or any subsequent condition) you can then reference the key using %palyload:foo-bar%
The period character is not allowed in data element names, so it had to be replaced...
Brackets are allowed, so you _could_ change this code to use payload[foo-bar] instead of payload:foo-bar if you wanted.
Anyway... The way that I put this together in my test environment was to create a single direct call rule that fires on any DC trigger that you care about. I set the rule order to 10 so that this rule will execute before the other DC rules on the same trigger:

This ^^^ keeps the mapping function centralized so that if you ever wanted to modify it, you wouldn't need to touch every DC rule. Note that there are no actions on this rule. Also, I used the custom condition for the key mapper so that the task will be done synchronously. Had I used a custom code action, the process would be asynchronous and would most likely not be done by the time the rule below is triggered.
Below is the typical DC rule that triggers on the same _satellite.track call, but executes at the default rule order of 50.

Here is the detail of the AA Send beacon call.
