If you know you want it for sure, and you are committed to owning it long term, go ahead and buy a new one and get everything you want. But if you pay retail, or more than 80% of retail, you'll take a bath if you change your mind and sell it. If you are not 100% positive you will keep it long term if this is possibly a test, seek out a good deal on a used rig in excellent condition that has been stored indoors when not in use. That way if you change your mind and want to bail, you won't take a big hit financially.
I did it that way with my 2006 Arctic Fox 1150 that I bought in 2013. It was an awesome camper! I kept it nice, and sold it in 2018 after 5 years of use for more than I paid for it. THen I bought my 1 year old Eagle Cap 1165 for 40% off new retail, and I'm sure I can at least break even on it if I sold it today. It's not so hard to spend a large sum of cash on something when you think it will hold it's value.
Finding the right used camper at a killer deal takes time, effort, patience. Don't worry about a used camper having issues, it will. But so do new ones. Just check it really good for leaks, rot, big issues and only buy the best.
Good luck, I think you will love truck camping!
