Buy lots of the rubber matting and place on the bottom of every cabinet/shelf. Helps to keep stuff from shifting around.
Buy those rubberized thingys that make extra shelves in tall cabinets, even works in some of shorter ones.
If the refrig isn't full enough to keep things in place, put empty bowls or pots in there to take up the extra space. Do that on shelves too.
Since we full-timed for 10 years or so, we had to carry a lot of stuff with us, that part-timers would never consider. So that kept cabinets, etc. fairly well loaded which also helped to keep stuff from shifting around, so it isn't much of a problem for us.
On our last trip we took out several heavy winter coats that we wouldn't be needing. However, that was a mistake and now my ironing board (table top one) won't stay in place. And we now have lots more space in that area, that I'll have to think of something to put in it. :-\
Think outside the box. If you have to put extra clothing in the living area to fill up cabinets, do it. Who's going to know except you and your spouse.
I've also used expandable book ends to keep books and boxes of food from shifting.
I've heard of others who put the couch decorator pillow inside cabinets when traveling to pick up the slack.
There's lots of little things that will come to mind as you "live in" your new rv, and you'll figure it out. If not right away, after a few trips. Work with what you have in it already with out lots of fancy stuff.
Oh, yes, we did have one cabinet door fly open "once", the one with the dishes in it. Luckily they were mostly corel. No damage. But from then on I've put one of the child-proof cabinet locks on it when we travel to avoid another recurrence. But I also rearranged that cabinet so that pressure is not applied to the door any longer, which is what happened in the first place. Both "fixes" has stopped it from happening again.
That's just a few ideas. Hopefully others will follow.
Daisy