Golf cart GC2 have nice thick plates, and decent isolation pads between the cells. The cases are also pretty tough. Golf carts do get a decent amount of vibration. The 6v batteries almost always have thicker plates. This is just geometry, half the cells in the same length gives more space between the plates to prevent shorts, and more room for thick plates (and support grids).
In the harshest of conditions, such as severe high frequency vibration, a quality AGM battery will often take more abuse. Even when the case is cracked, they will not leak, and will continue to work for quite a while. If you repair a case break in good time they will have minimal impact on life. The fiberglass mat provides isolation and cell support, as well as damping the tendency of the plates to vibrate. The vibration can cause the interconnects to crack, or the cells to short out. A very high quality AGM (Lifeline for example) will usually have a additional layer of separation/isolation between the cells, usually a permeable polyethylene plastic.
Most AGM cannot be equalized to recover capacity lost to sulfation. So they need to a good charge regimen if cycled deeply. Solar, etc is often required. Some do allow occasional "equalization" Lifeline will tolerate a 15.5V equalize/recovery charge after a extended period without a true 100% absorb charge.
Ideally you would have the battery mounted securely, with some rubber if severe shock is expected. An often missed problem is unsupported cables or fuse blocks mounted to the battery terminals. The vibrating cables transfer lots of force into the battery, and can cause failures. So support the cable as close to the battery as possible, and avoid attaching rigid items directly to the terminals (bus bars etc).
I am not familiar with your vehicles alternator system, but sometimes a higher voltage regulator is available (or can be made DIY). 14.1-14.4V is a decently high voltage that will charge your Aux most of the way, and won't cause undue stress on your starter battery for extended drives.
