One more question... If you only had one DO and were typically cooking for 3-4 people, would you start with 10" or a 12"?
For 3-4 people, we use our 12" and then refrigerate any leftovers for lunch the next day. Cook once, eat twice.
The basic equipment in addition to your d.o. that I recommend:
Welding gloves (I bought mine on sale at Lowe's for $5).
Lid lifter
Spatula, ladle and meat fork
All of this fits in 1/4th of the space under one of our dinette seats. I put the d.o. in a milk crate and lay a dish towel on the d.o. then set the lid in place... no rattles. The gloves and lid lifter lay on top. The spatula, ladle and meat fork are in the kitchen drawers.
Now charcoal can take up as much or as little of the space as I want in the basement storage. I usually take a ten pound bag with me and replenish the supply if we're out camping longer.