I would do a high quality black stain over oak for the outside, I would use 1side good oak plywood, less likely to warp and is cheaper than solid oak(oak grain shows up the deepest), then finish the edges with solid oak trim. after you stain it, I like glossy so I would clear coat it with a high quality oil based clearcoat, basically get the most expensive one.... spay cans will apply smoother, this will finish the outside nice. for the inside I would silicone all the joints with a thin bead smoothed with your damp finger, then when dry, paint it with a marine epoxy paint, pick whatever colour you want, I use silver alot as it reflects ambient light. Do multiple coats of marine epoxy inside the canopy, you will have a nice canopy that wont warp or fall apart, I use stainless screws and waterproof wood glue and countersink the screws and cover them with oak plugs. I used to build custom cabinents for show homes, this will work Ive done it many times, Spry clearcoat outside or you may get too high and start eating the paint...lol