Most LiFePO4 batteries advertise that they can be stored/used in almost any direction except upside down (concern about the terminals I imagine. About every battery I looked at specified how it could be use. It wouldn't be hard to find ones that can be used in multiple placements as there is not anything to really leak out/vent in most cases. The manual for all the major brands are typically available to download.
And the iPowerqueen 25.6v 100Ah manual says it can be used any direction except upside down.