The main problem with long gear is shape, not weight
Tripods often look small enough to tuck anywhere, but their length and rigidity make them far more disruptive than their weight suggests.
On a Xinjiang road trip with repeated boarding, bags and rougher segments, one loose long item quickly turns into a cabin management problem.
Footwells and door areas feel convenient but create repeated risk
A tripod near the feet may seem fast to grab, but it can interfere with boarding, jackets, bottles and simple seat movement.
Near doors or seat gaps, long gear is also easier to knock loose or forget when the group gets out quickly.
A fixed long-item slot is usually the steadiest system
Most groups do better when long rigid items live in one predictable place, such as a side edge of the boot or a dedicated sleeve.
That system works because everyone knows where the gear belongs and whether it has been returned before the next drive.
Quick access should be reserved for the one truly high-frequency item
If one tripod will be used repeatedly throughout the day, it can justify a quick-access slot, but only if that slot is clearly safe and controlled.
Quick access is useful. Random temporary placement is not.