Ben
I had exactly the same requirements as you and ended up with a TR182, though a normally aspirated fixed gear 182 would have been fine. I reckon you lose 10-15kts vs the RG in the cruise when you don't put the dangly bits away.
Realistically, with a family of 4 (2 teenagers) and a bit of luggage (you have to be harsh on the ladies) I can fill up with 260 litres (334 litres is capacity). This will give me 6 hours endurance at 42lph and 138kias without reserve. Frankly, 2-3 hours is plenty in a light aircraft with my family.
I beg to differ with achima on the grass. I fly mine off a very short grass strip very successfully. The only issue with the small wheels is that they can sink into soft runway and taxiways more easily than other aircraft in the wet uk winters, particularly if you are 4 up. I've needed a push a couple of times over the years.
And the grass is more forgiving for the odd 2g landing vs Tarmac, provided it isn't too frosty.
The turbo is nice to have but not essential. With it you can get full power (31 inches of MP) on takeoff no matter how hot the weather. You also get superior performance at altitude. I have no issues cruising around at 140kias at 42lph (though you need an edm700 to watch CHTs). I've also cheerfully cruised along at 171kias, thought it's not economic. Most of your fuel is used to cool the engine!
Landing a 182 is a doodle. I've put one down with 4 adults on board on a 261m grass runway. To be fair there was a thumping headwind, but the 182 in all her variants is an impressive aeroplane and I am chuffed to bits with mine.
I would strongly suggest you try out all the options before coming to a conclusion. It's still a buyers market out there.