I just finished a nine month tour of South America and Canada and I did it with a tiny one person tent that I could set up anywhere (http://www.mec.ca/Products/product_d...34374302885935). It was very light (1.3kg) and wonderful and was actually spacious enough to fit me and all my gear inside. In addition, I was able to cook in the vestibule! Obviously I could not fit my bike in it so it was left outside. Very very rarely did I lock it and it was fine. For half of the trip I didn't even have a lock.

3.5kg seems huge to me but it depends on what you want to do with it. If all you want is somewhere to sleep then it's too much. If you want to set up camp and chill for days at a time then maybe it'd be worth carrying it around. As for security, I wouldn't add several pounds of gear just to put your bike inside. You also have to think about where you want to camp. If you plan on bush camping you'll have a hell of a time finding a spot big enough for a large tent.