Anything can be modified ;-)
Shoot an email to Ron at MLD and ask, he'll let you know what it would take and what it would cost.
Personally, I like having a separate rain jacket. If it's raining, I want to set up the tarp first, then the hammock, and still mill about the campsite chatting with my companions, without getting wet.
I hear ya about 'gaining' weight by hammocking. To me, though, it's been very much worth it. I simply sleep significantly better in my hammock, and that's worth a little bit of gain, especially since I've cut out so much other weight from where I started.