Puppy in car - recommendations for harness / "carseat"?

[PuppyVsCar]

Hello Doghouse! Photo tax pre-paid of my 13 week old Labrador-ish puppy (there's some Beagle and Springer Spaniel in there too).

This boy is the perfect puppy with the exception of car rides. He HATES the car, sobs the entire time he is in it. After his vet trip today for his second round of vaccinations I had a real battle even getting him back into crate.

I am very aware we need to work on building positive associations but I think there is no way to do this when he is in a crate in the boot - I think for him his anxiety there is as much about not being able to see me as being in the car itself, and once I shut the boot he goes straight over threshold. I am wondering about getting him a clip-in harness and also keep getting adverts for these dog "carseats" / bolsters that go on the seats. However there seems to be an overwhelming array of options and I'm finding it difficult to know what is actually safe vs just well advertised...

I'd be incredibly grateful for any recommendations!

They're safest in a well anchored independently crash tested crate designed for cars. Such as a transk9

Chucking them in the boot and just using a guard along the back seats seems no safer during a crash than anywhere else in the car.

In terms of the dog being a fidgety distraction and CAUSING a crash then yes, in the boot one way or another is better than in a contraption in the seat.

A lot of people either don't realise you have to use restraints on dogs in cars or don't care. I've seen a lot of dogs in front and back seats, sticking their heads out of the window and quite a few people driving with dogs on their laps.