The end of year/season works well. The only items exempt from that rule are emergency supplies.
For canned goods, I just stock about 3-4 days worth of quickie meals over my planned menu. That means about 9-12 cans total for soup, beans, chili, etc. Gives me an emergency food ration if needed (or more usually, something easy to fix when I just don't want to mess with cooking).
Double duty works well for "special" trips. I go to a clipper rally twice a year. It's the only time I cook larger quantity meals. I used to carry a large frying pan and a large pot and a casserole dish. The latter two only got used for the rallies. Now, I have a large straight low walled pan that can work as a fryer, pot or casserole dish. It gets used all the time.
The other thing I've discovered is that if I require myself to find a place in the RV to store it before I buy it, I buy less stuff I don't really need.
1975 American Clipper RV with Dodge 360 (photo in profile)
1998 American Clipper Fold n Roll Folding Trailer
Both born in Morgan Hill, CA to Irv Perch (Daddy of the Aristocrat trailers)