What appliances are you talking about? How heavy and unstable are they
I keep a hand mixer on the bottom shelf of my pantry cabinet, and a stovetop coffee percolator in a different cabinet, and that's about all for appliances that are not built in. Maybe at some point I might add a crock pot (and perhaps an inverter to power it while on the road), and it would probably end up living in some lower cabinet too.
In general, things seem to be reasonably secure in cabinets on the road, though a whole lot depends on how smooth and level the road is. The hardest for me seem to be dips when entering and exiting driveways and the like that cause substantial side to side leaning--not very harsh for the passengers compared to big bumps, but very capable of rearranging the contents of cabinets and occasionally spilling something onto the floor. The propensity for the latter depends to a reasonable degree on how firmly the cabinet doors latch shut.
I have had a couple of plates (nice heavy plastic ones) break from falling to the floor. I also had a watermelon get loose once; I learned from that to keep a watermelon in something other than the pantry cabinet, as it will get quite a head of steam up when it rolls around. Inside the dinette storage under the seat works nicely for watermelon (for me).