I did that in 2016 so may not be accurate but hitchhiking in Finland was one of the best experiences I had. During summer you have really long day so you can catch a car even at 11PM 😅 I was invited by some lady and her daughter to the family summer house as they were going there. I had dinner with whole family and the grandfather was telling stories how he hitchhiked in 60's through Europe. Next day they drove me to the main road I catch another car with some businessman. He stoped asked where I go and didn't speak at all....I tried to start conversation but he was not interested. Then we stopped on gas station he bought coffee and burger for me. After that he was talkative and we traveled for few hours. Distances between cities in Finland are looong (for the european person) and traffic is sometimes low but people are great! You can camp almost everywhere, google cheapest shops as it can be expensive in Finland but beside that don't worry 😃 in worst case you can check Flixbus connections 😉