Delay/Disruption Tolerant Networks: Anyone with experience designing/implementing DTN gateways as overlay on top of TCP/IP network?

Looking into DTN as a side project at work - assuming the current install base on IP devices is not going anywhere any time soon, I'm looking at the plausibility of using DTN as an overlay to protect certain parts of the network that are connected over highly unreliable WAN links or links that are only opportunistically available.

Would be interested in bouncing ideas off anyone who has deployed something like this.