GTM/DNS as a smart DNS server ("without" LTM)

Hi,

I am trying to figure out a way to use F5 BIG-IP GTM/DNS as a smart DNS server only. The idea is shown in the figure below.

There a two data centers with GTMs, LTMs and servers as shown above. Let's just say that we don't want to place the servers "behind" the LTMs (and forget for a sec all the good reasons why they should be behind an LTM) from a client's perspective.

The client would like to access a service at a fqdn. The LDNS queries one of the GTMs. A GTM returns the IP of one of the SERVERS, NOT a VIP. The GTM also needs to know if the servers are UP, so some form of monitoring is required (probably done by an LTM). Load balancing is also required, but a simple Round Robin would do.

I haven't found an elegant way how to accomplish this yet, perhaps this can be achieved with an iRule?

Any ideas appriciated!