I always tour alone (because I'm a miserable old git), whilst I was initaly a bit aprehensive on the security front i soon got over it. The majority of campsites, more so in the summer, tend to be littered in things more valuable than my bike and possessions. Every b&b and hotel has either had somewhere fairly secure to leave my bike or been happy to let me take it to my room, if you pre book a disabled room at the likes of
travelodge they are easily accesible.
The only issue is normaly lunch or shopping stops but i tend to avoid the major towns if i can so you can normally leave your stuff in plain view. At supermarkets i try to leave it either in view of the security guard or by the big windows so its in plain sight. I just use a cheapo wire rope type lock and run it through the back wheel, frame and pannier handles and round a handy bollard or post. I keep the valuables in a bar bag which comes with me.
Because i like a bit of comfort my set up weighs about a million tons so their not going to get a quick getaway even if someone did take a liking to it.
I think we underestimate many peoples honesty and i cant see a touring set up with panniers full of dirty washing and soaking wet tents being of much interest to the oppertunist thief.
Come on the warmer weather, i cant wait to get the tent out and get back out on the road.