Anyone who thinks their camper is automatically covered under either their auto or home owners policy would be well served to read their actual policy to confirm that coverage.
Most auto policies have very limited coverage for "additional equipment". The policies I have read usually limit that coverage to $5000.
Homeowners policies are the same.
Does it make sense that insurance coverage would cost the same for a vehicle that is valued at $50,000 (truck alone) as it would for one that is $80,000 (truck and camper)? Maybe some policies work that way, but I would make sure to read it and verify before you get into a situation where you need to make a claim.