I use an air nozzle to blow all the crap out 1st, then shop vac. After that we have a carpet cleaner with hand held part. Spray everything down with a good cleaners and suck it all up. Thats for the floors and carpet. I have another steam cleaner that can be used on all the other surfaces to loosen dirt, grime, etc. Then good microfiber towels to wipe everything down. A good cleaner/disinfectant will also do the job.
The interior of the truck I bought was filthy. Took me hours of cleaning so it didnt stink. Now I can just wipe it down most days and a deep clean once a month or so.