Why not just get a smaller car and use a tow bar rack for the bikes?
I used to use a big old Thule towbar rack (Since sold for a small profit), and in fact we needed it for the estate cars when travelling down through Europe and for camping etc etc, as there simply wasn't enough room in the car.
Space to store one of these things is huge and they are pretty heavy, plus you need to get a towbar fitted.
I REALLY dislike the bikes being open to the elements, so that was a strong driver to getting the vehicle we have - for reference it's footprint on the road is smaller than most luxury SUV things, X5, Q7 etc etc, which I detest.
Additionally, on a lot of our journeys down through Europe, we have to stop off for maybe 2 nights on the way down, and 1 on the way back.
As it is I am hyper conscious about the bikes being at risk of theft, but the van has fairly dark tint, and I cover them up as best I can inside with old duvet covers to at least disguise them a bit, plus we try and choose places to stop with either secure parking, or not on a major thoroughfare - so far there have been zero issues.
With a rack on the back, the bikes would be open to nasty weather, as well as advertising themselves to anyone of a thieving nature, so not desirable for me.
The beauty of the van shaped vehicle is that we can get 3 bikes in, 3 people, plus camping gear and luggage, all without needing a roofbox.
I do still have a roofbox, which we have used when travelling down through Europe with 4 in the car and 1 bike, so still a useful flexible storage option.
I'm WAY more happy/comfortable having the bikes inside the vehicle with me, but I know a lot of people are happy with them on a rack, or up on the roof, I'm just not one of them :-)
EDIT: And to add, my partner's job is to run sort of educational music classes for pretty small children at various locations, so although she uses a cargo bike for fairly local settings, when she has to travel further she will use the van.
She has LOT of kit to cart about, and for simplicity a fair chunk of it lives in the van - if we swapped to a smaller vehicle, she would have to spend far more time ferrying stuff in and out of it, and we'd need a load more storage at home.