Ok you can actually leave the spider in the tanks, just remove any hides or anything that can move around and hurt your spider, then you can travel with in the back of the bakkie.
It is almost better for them.
Just put them under every thing so they don't get direct sun and close to the back, then they will be fine.
Since you leaving early in the morning you will be in PTA before it gets to hot, and anyway it is getting colder so you really don't have to worry about the heat, you will be in PTA in the early Afternoon.
just stick your lids down with tap to stop them from moving around.
If you don't feel happy about doing that way, you can use the plastic deli cups you have and just put them in a night before you leave, you can also put then in the back, close to lid at the back so you can also stop and check on them if you worried about them. Also avoid direct wind.