given the voyage design, there is maybe not enough surface area for a backless case to grip without blocking the page turn buttons.
i used a thin solid push-kindle-in-to-grip shell case that added little to the overall weight and folded back unobtrusively in portrait mode
here is a cheap silicon option. at this price you can afford to carve up a few in search of backless
https://www.amazon.co.uk/Kindle-Voya...oyage+silicone