Camper painted
* highlights from hindsight, aka "Learn from our mistakes": Prop the roof of the camper up before you get it spray foamed- it will solidly hold the form it is in when it's sprayed. Also put the windows and roof vent in and mask them all off good with garbage bags, before spraying. See this post. Take foam off in little layered chunks instead of trying to make it smooth - see near end of this post.There's been progress on the camper front. After a long hiatus, we've got it painted inside (mostly).
This stage was delayed because in order to paint inside, we really needed to be able to pull everything out of the inside, and that meant having a roof to move everything into.But at long last we did it. When we pulled all our stuff out we got to fix a few things, add some screws where strain had been showing, replace the floor underneath the bed, run new wires to the brakes, and a few other adjustments and improvements.
The big job was definitely carving the spray foam insulation. As we were advised, we got some bread knives from goodwill and went at it by hand. Whoowee, what a job. H.W. did the majority of the labour while I was fidgeting with other things, but what a task. Early on we surrendered the idea of making it look good, or smooth. That was out of the question.
Even flexible knives are hard to work when held in a curve, and that gets old over time. Then the blades lift little crumbs and chunks out of the foam.It didn't look very good, and it was tough sawing away, really tough to work with arms overhead for so long. We decided we'd be satisfied with more consistent headroom and taking down the major protrusions.On the bright side, it improved greatly when it was painted.
The carving was long and hard and exhausting. All the crumbs of foam clung to us all over with static electricity and trailed us around like PigPen. It was a huge mess. We ruled out the sander early - it made an even finer, messier dust and didn't have great results. The grit immediately filled with foam and was useless.
So it looked bad, and we let go of that and just beavered away at it until we couldn't take it any more. H.W.'s thumb sustained some damage from flexing the knife all the time and had to have a day off. I emptied a couple cans of expanding foam in little voids, hidden cutouts, and burying the tail light wires into the wall. It acts like glue, really sealing the framing into the body of the camper. I also sealed the edge of the arborite sheet we laid down under the bed as floor with foam.
Next we painted, and things went from bad to worse. Rolling was out of the equation with the irregular surface so we dabbed and dabbed and dabbed with brushes. The foam and all the pores and gaps in it sucked it right up, so that we ran out of paint early and just barely were able to cover the visible areas, leaving orange in all the cupboard spaces. 
That was a really depressing stage. It's one thing when you see results for hard work, and another when it takes longer and is harder than you expect and it doesn't look good.The rough foam prevented painting (cutting) a tight line against the wood trim around the windows, or the cupboards, or countertop, or anywhere. Ugh.DAP to the rescue! I decided latex caulking is pretty much paint, only thicker. I caulked around all the windows, really pressing the tip into the foam and smearing it out into the painted area. 
We were using untinted paint and brilliant white caulk; this may not fly so well with coloured paint. The expanding foam out of the can, much less dense than the spray foam, accepts the caulking much better; it kind of permeates and impregnates the foam, hardening stiff. And once there's a bead around the edge, it's much easier to paint up to. So caulking saved the day, making clean transitions between foam and Corex and shelves, etc.What we didn't expect was how the look of the painted foam would change. The parts that really looked good after painting were where I had taken slices out of the foam in layers, sometimes it made a herringbone pattern. 
This was largely my work, as I'd gotten lazy and was just trying to take down the material and not make it fancy, hacking chunks out. Painted, that looks kind of cool, almost like rock. I suggest tackling foam in this way from the beginning. There's going to be texture one way or another.Slicing layer after layer is an easier motion to make, too. Slice in and snap off the chunk of foam.
After that, it was just reinstalling the Corex/Coroplast we'd unscrewed to paint around, putting the doors back on,and reloading all our stuff. The whole event was about five days.It doesn't look bad. It's much brighter with all the white, the curtains look sharp, and there's more clearance everywhere. The painted foam is sealed, no longer crumbly. Inside closets where the foam was cut down and not painted, it sheds crumbs at a regular rate. Someday I'd like to seal all that in with paint too.
There are still touchups and more caulking to do, because we didn't have the luxury of time to really finish the minutiae, but the big things are done, and importantly, we shouldn't have to dismantle the camper again, or even move out of it wholesale.It's sort of adobe like, or like stucco. It's a cozy natural texture.Closer to finished!
Last camper post, and the full collection of posts about our fiberglass egg reno.