I've stopped in Ullapool many times over the past 20 years and have never had a problem parking on most of the streets and also the campsite. I have parked it on Shore Street outside youth hostel loads of times and just put a disc lock on and never had any cause for concern. You should be fine, enjoy your weekend, Loopallu is great, I wish I was going this year.
cheers. 2500 pissheads including my self worries me a bit should be fine. this is my 7th visit reef playing this year, watch out seaforth hell is a coming.
Don't park your bike anywhere because the natives will complain and you should be fine. I hope you have been to Ullapool before, it is only a very small place where lots of visitors came. So just be careful about where you put it.
