Generally, I'd rec. the following process, similar to what the other guys wrote. However, your camper is so big that you'll have to tweak for your needs. The roller idea idea mentioned is a good thought (w/ an exterior enamel or oil, acrylic will chip -good for top coats, but not base!!!!)
But you also have so much art on there already, that 'base colors' across the whole body 'would' require painting all that current art over and redoing it on top of the new colors.
Anyway:
1. Thoroughly brush/sponge wash the surface -either at a car wash or bucket at home. Use very soapy water, or Simple Green, or that Orange Cleaner stuff to be sure you leave nothing behind (ajax could work too). Let bake-dry in sun a few hours.
2. Sand the surface with light sandpaper, or even brillo pads will work. This gives the surface 'teeth' for the new paint to cling on to. It only needs to be lightly scuffed.
3. Wash surface again with hi pressure water (& clean sponge -do not use paper towels or most cloths! -they will leave lint behind every time!) to get rid of sand/brillo filings/shavings. Floating pollen is also a concern if you're not doing this indoors. But there's nothing to be done about that except season and timing of day. Let bake-dry in sun a few hours.
4. I paint the surface black first -several coats. This ensures maximum coverage of the old colors. And if you want black panels lines later, simply get some pinstripe tape for the next steps.
5. *Silver coat* (This one could go first). Going silver means that after your top coats are complete, you buff them away and get a bare metal look by scuffing down the top layers first. Again, several coats always.
6. Top coat color -whatever you wish. Several coats. This does not mean colors for stripes. This is the real 'base' (factory) color of your ship. Everything else (stripes, logos, details) goes on top of this.
Note: I threw down about 7 base coats and a few months of road use later, there were chips that went right down to the factory coat. The thicker the better.
7. Blue masking tape (not regular cream kind -leaves goo behind often) and newspapers for larger areas (newspapers leave newsprint behind often -this can work to your advantage depending or be your worse nightmare,a fter the pollen factor). Put down edge of blue tape first and rub down paint side. Then use more blue tape to put newsprint down. Again, rub the edge down tight.
Note: Spray paint will get into every place that you let it!
Be sure to thoroughly rub down edges with the your fingernails. ANY gap will result in overspray -which can be fixed later, but getting as much possible right the first time is best.
I've used clear contact/shelf paper to good success. Cut a new stencil for every logo everytime, even if you have multiple logos. Once you paint over clear contact, it is no longer clear and defeats the purpose. The time spent cutting a new logo is small compared to the time needed to repair a bad paint job.
Also, search dry transfer/ water slide decals on the net and you will find paper suppliers that sell this stuff. It goes right through you inkjet and the sealer they also sell will fix the decals in place on paper for the transfer. I was going to do this, but fate had different ideas for my bike. I will be doing this for my scale models though.
8. Always work background colors to foreground! The tiniest detail go last, the biggest coverage colors go first.
9. Seal with multiple layers (3-7) of clear flat or gloss, your pref. Any 'repairs' you made, if they are the same exact color and paint type (enamel, oil, etc) as the original paint will (should) vanish with the sealer on. this gives everything a nice uniform feel. My main paint was spray enamel, I did repairs with Testor's model enamel paint. Immediate result was ugly, with gloss spray over, the repair disappeared -your results may vary
Note: Turn off the wind, or if you do not possess that power, wait for calm days. It will blow your spray stream everywhere except straight ahead and blow your newspaper everywhere while you try to tape it down.
Note: If you do this in a garage get as many fans as possible and always blast them on high -severe brain damage will occur otherwise with that much paint going on.
Note: Home depot white and black are a buck a can. Other colors can run up to $10 each, but are worth it. Rustoleum is the most common after generic cans. There are others. To go pro and spend huge money, go to an auto body supplier and pay $$$ per can.
Note: Mixing spray can colors.
If you have medium red and want it dark, paint over black. If you want light red or pink, paint over white. Or for metal colors, paint over silver first. Apply the top color from far away very lightly. Move in closer to dump more top color onto the bg color until you get the right tone. Not a perfect solution, but from a feet away will give the illusion of the new color.
Note: If you are an artist to begin with, throw down that $150 for the airbrush and compressor you've been thinking about these past years for any stylized custom paint work -such as 'nose art' as found on WW2 bombers and such. A basic brush/comp is adequate. Cheap AB's go for $30 range (and up to $200!). Same for compressors, except cheap starts at $~100 and up to $500. Don't bother using can s of air, they get cold too fast and you will spend more on them over a short time than simply buying the compressor outright.
For more details and thoughts, check my site. I go through every step, misstep, hassle and ingenius glory I had while painting my bike.
www.twinlitworlds.com/vf1a/html/index.htmlHave fun!