Well, as someone who is pretty weight conscious, this should be interesting. First you have to really decide exactly what your mission is, because if you want to go camping, you need extended baggage, perhaps extra fuel, some beef ups here in there to handle turbulence, and the extra weight of camping gear and pax.
If you just want to build a point A to point A airplane, that’s a different mission. with that mission you might be able to get it down to 900 pounds. To get below 1000 pounds, with a true backcountry airplane, it’s going to take some really really really serious work.
Since you are experimental, you can go with a battery 2 1/2 pounds, starter 5 pounds, and a lightweight fly wheel 2 1/2 pounds. So you can save 10 pounds going no starter. If your mission ever includes floats, I think that would be a very good 10 pound investment. Trying to hand prop from outside the cockpit while you’re drifting down current, into the trees is pretty challenging.
There are a lot of quite knowledgeable people on this site that can help you obtain your goals. And we would be very interested to follow your progress and learn ourselves.
Bill