Throw in a few stimulants (Cocaine/speed) and it may not seem as strange.
If I planned on going camping for the weekend, I would have probably left as soon as possible after getting home from work on Friday. If not that, I would have went to bed early, intending to get up and make an early start of it Saturday morning. It seems strange to me that someone would plan on going camping, then head to a bar to drink all night, and if you're correct in your assumptions, do drugs, then get behind the wheel of a motor home, or any vehicle, and take off on a road trip. It seems strange to me.