Really depends on age/size of kids and whether you want to be officially DOT legal. Installing a lap belt or, better yet, 4 point seat belt in center would provide safe, though not the ultimate restraint for the third passenger if only using a lap belt. Any kids over 11 are probably going to be squeezed so wouldn't expect them to be happy for any distance and certainly not off road.
Amazed I managed to live long enough to start using seat belts. First car that even had seat belts was a '67 MGB I bought new in AOCS in Pensacola. They were only lap belts and never used them. Later during flight training picked up the habit of buckling in and it carried over to driving a car. Now buckling up is second nature even without the annoying seat belt nanny buzzer. My InLaw counter part is a hard core no seat belt guy and goes to inordinate trouble to sans seat belts and not trigger the warning. Rather stupid when you see the people that are killed in vehicle ejections while all the others with their seat belts on survived.
Amazed I managed to live long enough to start using seat belts. First car that even had seat belts was a '67 MGB I bought new in AOCS in Pensacola. They were only lap belts and never used them. Later during flight training picked up the habit of buckling in and it carried over to driving a car. Now buckling up is second nature even without the annoying seat belt nanny buzzer. My InLaw counter part is a hard core no seat belt guy and goes to inordinate trouble to sans seat belts and not trigger the warning. Rather stupid when you see the people that are killed in vehicle ejections while all the others with their seat belts on survived.