A simple idea about wreckage: Its health level should be indicated by how dark the wreckage is. Undamaged wreckage should be light and metallic in appearance. Heavily damaged wreckage should be dark and charcoal in appearance. If wreckage health isn't being sent to the client already, hopefully that wouldn't be much of an issue.
I don't think that will look very good cosmetically. I also don't really see all that much point to show its HP, they are all so low that just a few shots will make it go away anyway. I think a better solution would just have it slowly degrade/disappear over time. The more metal the unit takes to build the longer it takes to disappear.
or just like in TA .. turn the wreckage into rubble .. units can go over it .. and the player is still able to reclaim it .. and its eyecandy too ! http://koti.mbnet.fi/wiitanen/Zero_Shot_047.png
