Your budget actually looks pretty healthy, and you've clearly got enough experience traveling that getting on the road won't be that unusual of an experience for you. I'd still try to make at least 1 or two small trips with your friend between now and then to get more familiar with camping (what you like/don't like, need/don't need) and to get used to traveling together.

Even there, when building your plan, try to find at least some time where the two of you are apart, and have your own personal time.

I will say the van idea seems pretty suspect with the budget numbers you're laying out. Buying a vehicle that's roadworthy for a major trip is generally going to set you back at least $3,000-4000, and then you'd need to set aside at least another $1,000 for possible repairs while on the road. If you already own a vehicle, that's going to likely be a far more cost effective option for you.