If you buy a deep water bowl and fill it 1/2 .. It shouldn't spill.... Unless you are driving a buckboard cross country....My amazons partied in there water bowls the whole ride down...
No buckboard, just a Mini Cooper, a moving truck, and a Subaru Forester.
I'm not too worried about spills anyway, they'll have smaller cups and be in smaller cages anyway.
Your golden... All nice riding cars... Albeit not the biggest but nice