Husband and I have to travel from SE Iowa to Fargo North Dakota pulling a camper there for his brother who’s moving. If we use our truck we have to take 2 vehicles. Our truck is a single cab and there’s 4 of us. His parents are buying a 1995 f350 full cab long bed. Our son will be 3 in July he was 36in and 35lbs at his last appointment. Our Daughter will be 1 in August she was 20lbs and 30in at her last appointment. They’re both currently in Safety First Grow and Go’s rear facing with seatbelt install in my car. They have Cosco Apt 50s son forward facing in middle seat and daughter rearfacing in passenger seat with airbag off in husbands truck for emergencies only. His parent’s said we could take their new truck that seats 6 so we don’t have to take 2 cars on the 9 hour one way drive. My question is, can the kids’ car seats go in the truck safely? I know it doesn’t have any latch system or tether spots so I assumed if I kept them both rearfacing with seatbelt install it would be okay but I’m not sure.