question

@Drommen, your dealer has given you the proper response... never mind the Jeep or the chop scenario: gravity is a strong, inexorable pull that's always present, no waves or bumps needed, and lead is heavy. You could stand them on their side on a stable floor and, eventually, one or more of those plates would probably fail because the internal plate support structure is simply not designed or tested to withstand lateral stress on the plates like that configuration would cause.

These are sealed batteries, of course, so they can be installed on their sides or ends or any number of other configurations without their contents spilling out, but the question here is a matter of longevity; the internal plate supports are not designed or tested for installation in any configuration other than in the "normal upright" position, so it's anyone's guess as to how long such an installation would last before the battery internals failed, and considering that this could potentially have disastrous results -never mind the waste of a perfectly good battery- I must echo your dealer here and say that installation in anything other than an upright position is not recommended and not supported - that latter meaning that improper installation would not only likely lead to premature failure, but would also void their warranty, which is of course the last thing you'd want in this situation.