Hey Karl- sounds like a pretty sweet arrangement! I'm coming to the end of my first major solo road trip, and I have some thoughts for you.
-Hitchhiking and Couchsurfing are fun, but both require time and effort. Hitchhiking is always an adventure- I did somewhere around 3,000km in my three months in Europe, and it really requires letting yourself go, and being prepared for the worst. Couchsurfing isn't so crazy, but it can be very difficult to find a host in major tourist cities, and in remote locations. The ideal places to couchsurf seem to be medium sized cities, as they have the best combination of available couches and lack of visitors.
-If you're hitchhiking/couchsurfing, you'll probably be shocked at the generosity you find. I've had a guy drive me 60km out of his way to drop me off at my destination, I've had countless free meals, and just generally met a ton of interesting people. I hope you have an opportunity to hitchhike/couchsurf, as it really is a one-of-a-kind experience.
-Pack light. Like, really light. Two pairs of quick-dry pants (I recommend full length NOT convertible to shorts-- you can just roll the legs up if you want shorts, and you won't look like a fool), two quick-dry shirts, a single pair of shoes (aside from your climbing shoes), 3, maybe 4 pairs of socks if you can't get away with sandals, tiny traveller's towel, a lightweight/compression jacket, and sleeping bag if absolutely necessary, a nice smartphone to act as your computer, and toiletries-- that's really about all you need. I packed far too much for this trip and have regretted it since. You can easily wash your shirts, pants, and socks in a sink or shower, and the shirts and pants should be dry by the morning. The socks you may have to hang for a while, hence 3-4 pairs. A light bag will make your trip a million times easier.
-If you're going the hitchhiking/couchsurfing route, look into camping/squatting in the area you'll be in- oftentimes, you can walk <100 meters into the woods and be invisible to anyone outside, which means a free campsite for the night!
-Try to reduce the amount of crap you own to a level that will allow you to store it for free with friends and family. I had a 10'x10' storage unit for my business, and all my personal crap, and was able to reduce it a bit, and then store it between my friend's house and my dad's house. Just make sure your stuff does't overstay its welcome.
-Challenge yourself to see how little you can spend-- between couchsurfing, hitchhiking, and eating groceries, I was mostly spending under $15/day (10 Euro) in western Europe, in some of the most expensive places to travel in he world (Barcelona, Paris, Rome, etc). I didn't suffer from it either- I learned new tricks like emergency peanuts, eating foods like bananas, red peppers, and salami, which all require no refrigeration, are delicious, and together provide a relatively balanced diet (I went heavy on salami as I need about 3500 calories a day just to maintain weight on the road).
-Stay in touch with your friends at home, but don't be too glued to your phone-- you might consider deleting/not installing the Facebook app so you aren't tempted.
Above all, don't sweat it when shit goes awry. It'll take a lot more than a lost day of climbing to kill ya, so roll with the punches, enjoy your amazing opportunity and don't be afraid to take a break at home if you get road fatigue.
Have fun!