We have often stayed the night at truck stops. There is a lot of truck noise but there is usually a fairly good restaurant (if you don't feel like cooking in the RV). Rest areas along the interstates is similar in that there is a lot of truck noise. Never had any problems at truck stops or rest areas.
Have also stayed at Wally World (WalMart) without any problems. Considered staying in a church parking lot once but there was no one there to ask permission so we drove on. With our environmental work we have also stayed many nights in open fields and forests.