Hi, I just tried Skybox again after a long time due to the USB update. It's come a long way!
As a VR180 camera user, I've been looking for a decent player for literally years now. As the OP says, for image collections, single-button prev/next is absolutely essential. This feature would make Skybox perfect as a VR180 player.
To keep it simple and not require full button remapping functionality, maybe prev/next could be a simple addition, for example thumbstick left-right while holding grip button?