Thought experiment: how many arcane spellcasters in a fantasy combined arms army

[Seward]

The squad druid also contributes with Longstrider castings.

Actually Traveler's Mount. Longstrider only works on you or your animal companion.
Also Easy Trail. In conjunction with traveler's mount you get a serious mobility boost for mounted troops.

The floating discs do have the drawback that they can't easily transport the mounted charger's mount, which is usually better in combat than a summoned one. This was an oversight on my part.

This is the kind of thing rafts supported by disks are best for. Once (and only once) we tried to do it with 4 discs. Probably be ok with a Paladin Mount or animal companion but lets just say when the rider failed handle animal halfway across the river it....well lets just say that was just a bad idea.

Although it would have worked if I had been high enough level that one disc could have handled over half of the mount's weight. The problem was it shifted weight and exceeded weight limit for one of my disks and it went downhill (literally) quickly. Horses are freaking heavy, they can exceed 100lb/lvl by quite a lot. The answer to that problem is dimension door if it is just something like a river, or water walk/air walk for longer distances.