Internet
1. Starlink internet [50GB/mo priority data, unlimited non-priority] - $250 monthly / $2000+ for flat mount hardware. I had/have the less-expensive RV/home dish (non-mobile) before the mobile flat mount high performance dish came out. I can quickly attach it to the Harbor Freight flag pole and hoist it above most tree canopy if needed.
2. T-mobile hotspot [50ish GB/mo] - Roughly $55 monthly. Works great in cities with 5G.
3. Verizon mobile router (Peplink) [300GB/mo] - $150 monthly for the data plan from: https://mobilemusthave.com/
The reason I have all these is because I need redundant connections to do my job. It's not acceptable to not have internet one day. Also I use MultipathTCP to bond all my connections together so my Zoom calls never drop (which used to be a problem with Starlink, but less so now these days).
Fuel Costs
This is my greatest expense. I have a very heavy Sprinter van that I built out myself. I get about 14 MPG diesel. It really depends what State you are in on what the costs are and how much you travel. The general consensus between all the people I've met on the road (working full time) is that they put about 35k miles on their vehicle per year.
Campgrounds
Really only pay for for these when on the East Coast since there isn't as much BLM or USFS land.
Power
I have 600 amp hours of batteries with about 800 watts of solar on my roof, 1320 watts of portable panels that I can set up when I need to (mostly when I want to run the air conditioner 24 hours a day). I also have a 3360 watt auxiliary alternator that will charge the batteries real fast. The truth is I run a ton of computer equipment and never really worry about power.
This lifestyle has been amazing. I used to feel stuck being an engineer behind my desk all day. Now when I get tired of a town I can simply move onto the next one. There's also some amazing groups out there and I've actually made loads of friends across the country doing this same lifestyle so we'll often meet up in places. For example, Trent (who arguabily started the "Van Life Gamers" movement) has a discord full of people that live this lifestyle https://discord.gg/d4xsZEVH.
I would also say having a Sprinter Van has been so much better than an RV because it's much easier to go places with the van than a huge RV. I can park at a trail head for example in a normal parking spot.