As with so many things in Spain it's "Yes, no and maybe"
There is a generic law that allows wild camping but almost every regional governemnt has put its own laws in place that restrict this - you can see a rough summary
here on my blog - to the extent that this law is only used to control camping on private property.
But there is a key distinction between camping - '
acampar-se' - and making a bivouac - '
hacer vivac' or '
vivaquear'
In this case your 'camp' must be clearly temporary, no tent higher than 1.2 metres and you only have between 8.00 pm and 8.00 am. All of these are still subject to the exemptions of National Parks and other nature reserves, the 200 metres margin from a shoreline, military or Guardia Civil locations . . .
There certainly are trespass laws in Spain and these work very much like the UK, being kicked in if you do any damage but also if you cross an abvious barrier, including just a sign indicating private property - usually the word '
particular' is used.
Almost all land in Spain is privately owned, despite appearances often enough, but you should be particularly careful on cultivated land, especially olive groves, and the region you are heading to between Madrid and Portugal, Extremadura, has an abundance of fenced off
dehesa that appears wild but is used for rearing the semi-wild 'Iberian' pigs, which are worth a small fortune, and are fenced in for mile after mile . . .
I agree totally with the 'no-fire' rule mentioned above, but this applies all year round as winters are often much more dry than the summer months. Regarding snakes, there are plenty of venomous types but the only real risk is if you tread on one while it's basking for warmth, like in the UK this makes them too sluggish to escape. But far more horrible are the creepy-crawlies, especially a
bitcho called the
Megarian Banded Centipede - park your bum next to one of these and it's ¡
Hola! time at the nearest hospital - and you won't ride home for a fair few weeks
Also, wrap up well in October, you'll be camping at over 1,000 metres most of the time
Regs
Simon