We’ve put the floor finish on hold temporarily so that I can do more research.
I'd already found a couple of products that we could use but then a professional floorer we met this weekend highly suggested using Watco Danish Oil with a covering of Minwax Finishing Wax for a really great finish. He also explained that if we ever get a big scratch or dings that we’d simply sand the area, reapply the finishes and the marks would have disappeared. Well, yesterday I looked up the products and the MSDS said it wasn’t all that healthy to apply. We have no idea if the stuff will outgas, and if so for how long, so we’re back to looking for all natural products.
Since our cottage will be mobile, our needs are possibly different than what a stationary house can use. What we’ve decided so far is that we need a finish that is:
No VOC
Water resistant
Flexible
Matte finish and a
Natural color
We aren’t yet sure what products we’ll choose but we’re leaning toward using an oil then a wax finish. The oil I like best so far is Bioshield Primer Oil. The write up describes it as a “deeply penetrating wood primer/sealer that creates and elastic, breathable…wood-grain enhancing surface…easy application…with superior water-resistant qualities.” Bioshield Penetrating Oil Sealer also looks like an option though it doesn’t specifically mention elastic, breathable or water-resistant.
Although Douglas fir a very soft wood, for the wax I’m thinking we should steer clear of anything with carnuba wax in it. I’ve read that it is a ‘hard wax that will continue to harden as it ages’ which sounds really great for a soft wood floor in a stationary house, but will it make our floor splinter when we move our cottage again later?

Since I need to complete the floor finish research, but don’t want to hold up construction progress, last night I put down a protective cover on the floor so that I can move on to wall framing. I duct taped together 4’x8’ sheets of masonite to protect our sanded wood floor from dings, dirt and scrapes as we attach the wall framing. Mike, a friend who has built his own home, professionally redone others’ (and also beautifully rebuilds antique cars piece by tiny piece), says that the construction industry uses thermoply to protect floors then throws it away. We didn't see a product with that name at our local home improvement store but we guess it's similar to masonite. We’ll either find another use for the stuff after it’s done its job on our floor or it will be posted on Freecycle since it will still be usable.
Have you ever used a No VOC finish for floors that is water-resistant and possibly flexible? What are your thoughts on our floor finish needing to be flexible?