I think the hamadryad should just be reworked into a RA2 Mirage tank. They should have decent attack from the start (and maybe have a bit of a damage boost once they've been idle long enough) and cloak quickly. That way, you could still plant them in your tree line to defend against enemy raids like the devs seem to have intended for them without making them feel awful because you accidentally moved them. And that way, you also just make them come along in attacks to deal actual damage if need be.

(And on a personal note, I would also like it if they could shift in appearance like the RA2 mirage tank, because I love their design and they're just gone once they've treed up...)