F5 BIGIP GTM/DNS VE with Microsoft Azure & AWS Cloud

I need to deploy the F5 BIGIP GTM/DNS VE as a POC, one in Microsoft Azure as Active & another in AWS Cloud as Passive with the Web/App servers added under each VE in the respective Cloud accordingly. Scenario is Web/App servers should be up & running if Azure goes down and seamless fail-over to AWS. Please provide me the solution for this scenario.

Also do I need to put LTM also..?