There is the possibility of a Murphy bed but for now, we believe an air mattress will be suitable. If we're mistaken, then we modify the box to accommodate - easy enough.
As for kitchen, ours is almost non-existent because when we attend model airplane flying events, there are usually several food vendors. Thus, we we can get breakfast and lunch on site. Then in the evenings, we go out for dinner with friends at a local restaurant. A compact propane grill allows cooking steaks, hot dogs, and hamburgers if I so please. Along with a microwave for popcorn or making grits, we're set!
However, during the day, we are busy flying our models (and visiting with friends) instead of being in the RV. Watch this 4-minute video for an example of what I mean about attending a model airplane flying event. Notice in the background you can see RVs and tents.
Thus, my use case is actually similar to that of people who attend automobile races and stay at the infield. Basically, it's camping out in the RV . . . but not in the wilderness because we are reasonably near civilization (5-10 miles max).
In fact, the only reason we don't stay in a motel like when we attend by traveling in the Bonanza and I am limited to bringing just one model is with the truck I can bring many models to fly! Plus there's a workbench for repairs (if needed). And lots of chairs so we can have a gab fest with friends!
Finally, when we're ready to head to bed, we run off the friends, lay out the mattress and inflate it - easy! In the morning it's the reverse because the same pump that inflates the mattress deflates it as well such that in just a few minutes it's ready to be rolled up and stored.
Anyway, we'll see how the plan works and adjust accordingly because if it turns out we'd rather have a bed permanently available we can easily modify the box. In fact, I have seen tiny homes where the bed is at a second level (dormer type?). This is an attractive possibility when combined with four 36" electric screws such that we can lower a platform bed to sleep, and raise it out of the way during the day!
By the way, you mentioned weather. Unless it's scattered summer time rain showers, we don't stay home from events when the prognosis is for rain! However, with respect to fast moving summer time rain showers, then we stay beneath the awning unless it begins to blow really hard when we simply run inside and hide until the rain lets up.
So many possibilities when you begin with a naked box!