The Haskell canoe also appears to be filled with sand. My skepticism had me looking very carefully at the photo but there doesn’t appear to be any obvious manipulation (which has been used to deceive long before Photoshop came along).
Tim - Hopefully removing the ‘glass didn’t peel off too much wood, and you shouldn’t sand too aggressively. But of course most restorations require some sanding and countless wooden canoes have been restored to become completely functional again. On the exterior I do as little as possible beyond re-clenching tacks and fairing the hull as needed (judiciously taking down raised areas). On the interior I don’t recall ever using sandpaper more aggressive than 120 grit, and often start on ribs with 150. Planking between ribs is usually sanded only with 220. The point is simply to avoid taking away too much wood, especially on the thin planking, and to keep tacks from being sanded through.
On the exterior oiling or varnishing will help rejuvenate the wood but won’t add where wood has been taken away. Sometimes fillers have been applied to the exterior apparently in attempts to fill divots at tack heads or to fill in where wood is missing or thinned. This is a recipe for disaster because, for one thing, anything that later comes loose under the canvas will cause problems.
In short, just take care and don’t be too aggressive. If pulling fiberglass takes chunks of wood with it, just replace those areas of planking. There’s no readily available means to test the strength of the hull especially since it will vary from place to place. In any case, these hulls were built to combine lightness and resilience. A careful restoration shouldn’t compromise those qualities.