12 days solo female travel in Maui on a budget

I’m unexpectedly in Maui due to work this October and I’ve managed to add on an extra 12 days vacation to my trip. I’m now trying to work out how to spend my time. I’m on a tight budget, as coming from Europe even the cheap options seem very expensive! I was thinking of splitting my time between a road trip where I camp and staying in private hostel rooms (I’m in my mid-30s so don’t want to subject the kids to my snoring in dorms). I was wondering if anyone can help me work out how I should spend my time?

My main priorities are nature, food trucks, hiking and snorkelling. I especially love rainforest and waterfalls. I live in a cold place and have had a busy year so I’d also like to relax in the sun. It’s my first (and probably only) time in Hawaii so I am open to visiting other islands too (I’m especially interested in Kauai) but wary of extra costs. Ideally I’d like to spend the money I do have in a way that will positively impact the local communities.

Any and all itinerary suggestions welcome!