This is a guide on how I did it for "Going Camping" achievement. You have to deliver in order:
Ore->Aluminum Ingots->Electrical Wiring->Electronics->Campervans.
Companies
Aluxion (Ore & Aluminum Ingots.
Betunija (Electrical Wirings).
Eumefa (Electronics).
Larus Factory (Campervans) There is only one place for this company, which is in Novo Mesta, (Slovenia).
Always deliver FROM these sites. (Can be other places, this is how I did it).
Ore: Use a steel dump trailer to deliver Ore from Aluxion, Niksic (Montenegro) to any company.
Aluminum Ingots: Flatbed trailer to deliver Aluminum Ingots from Aluxion, Podgorica (Montenegro) to any company.
Electrical Wiring: Curtainsider trailer from Betunija, Zadar (Croatia) to any company.
Electronics: Curtainsider trailer from Eumefa, Tirana (Albania) to any company.
Campervans: This one you have to use trailer especially from that company, you find company Larus, Novo Mesta in Slovenia.
Sidenote: You can do other deliveries in between, it wont affect this achievement, just make sure you do in this order for the achievement.