I use two 907 bottles, one for a portable camping gas two burner, we prefer to cook outside if its nice weather, and always fish cooked outside in any weather if one doesn't want to drive around with a smell in the van.
Its much easier and convenient as a back up to have two bottles. If one runs out its very annoying. It happened to another Cali I was travelling with in North Norway and its extremely hard to get a 907 replaced or refilled there, took a few days to be sorted.
Ive had my van for 3 years and I often left the rear gas tap on, this is something I wont do again because, apart from any other good reason mentioned by others on this thread, there are reports that it stretches the membrane in the regulator. This makes sense, my second burner wasn't working well for a long time and then eventually both didn't have enough pressure to work. I used to fix the regulator to get it going by tapping it, probably loosened the membrane I guess, but eventually had to change to a new regulator. This was supplied and fitted by a VW garage whilst on holiday in France for 100 euros.
For smaller trips I keep the little one burner stove for cooking outside which has a pint sized bottle with it. They are around £2 each, very safe, effective and small, stove can be placed just about anywhere.
Usually I also have an extra Décathlon £15 light portable table in the back too so that its easy to have somewhere to cook on etc with interfering with my VW dinner table.
That's my contribution on the subject, have a great summer and stay safe....