I just used 2 bar tacks, hopefully they will hold. The real stress point seems to be where the gusset taper part meets the lid, it pulls really hard there.
Originally wanted to do one out of all Sil Nylon, but opted for dyneema for the lid. Maybe I'll try another using all sil nylon but running some grossgrain as reinforcement along the lins of the straps.
Pretty amazing the force you can generate by cinching down on the straps of these things.