I'm also curious how/if the Army can build in IED suitability onto a light tank - it appears to result in a rather large weight penalty for the GCV.
I can think of a vehicle that meets all but one of the stated requirements already in the inventory. It's called a "tank". Like yourself, I noted phrases like "protected', "overwatch", etc. and presumably, "protected" means against IED's as well as direct fire. Unless there is some new miracle material that affords that kind of protection at ~1/3rd of conventional MBT weight, then that air mobility will have to be sacrificed.
For a few older members, this is going to sound a lot like "deja vu all over again". I suspect those requirements are going to require either a lot of refinement....or modifications. They seem to be asking for an RV that's 36' long on the inside, and 22' on the outside. It won't be the first time.
And after it's designed, will it be determined that it has to swim, too?
Sorry, age and experience have made me cynical...and occasionally, snide.
...and how are we going to pay for this little trinket, "constrained resources" being what they are?