For the Tybee campaigns, we typically covered all expenses for the ground crew and had at least two Hotel rooms at each stop. One year I think we actually ran three rooms once when we had a bigger crew and could afford the privacy. I figure those averaged about $130/night per room thanks to some of the deals the race management cut with the hotels (but that was some time ago). Some were up to $180/night, some at $80/night, most around $110-$120. Food at $35/day is probably a minimum. A little privacy goes a long way toward low stress. Ground crewing sounds like a relaxing jog up the coast but it is absolutely hard stressful work. Sailors need to do all they can do to help ease that work load - pack your own stuff up neat and tidy in the morning, make a reservation booklet that has all of the reservation details you can possibly think of (including who you spoke with when making the reservation), preprogram the navigational points in the vehicle's GPS for each stop. Oh, and take extra towels. South Florida hotel staff gets irritated at extra towel requests and will set the alarm clock in the vacant room next door for 3am. ;-). Buy plastic laundry baskets for the crew to have on the beach so you can throw all your wet gear and equipment in when you get to the beach each day and you can haul it to the hotel room yourself. Set that basket in the shower and rinse the gear out while you shower yourself - that helps to keep the stench of briney death to a minimum as the weeks go on. Have a set routine for changing batteries, charging, and programming equipment / devices before going to bed each night. Routines cut down on the morning pre-start chaos and you discover things in time for everyone to react calmly.
Also think hard about how you split up the rooms if you are getting multiple at each stop. You might want to split up sailors and ground crew so one sailor one ground crew per room - everyone is teamed up together during the day and a short little change of personality for the rooms might be a good change of pace to help maintain the push through the two weeks. Additionally, the shower schedules work out better that way - the sailors can both hit the showers in the different rooms at the same time which usually does not coincide with the shower schedule of the ground crew (and, btw, get ground crew that does shower regularly ;-).
A spare boat like Mike has done is a luxury and it certainly relieves a lot of stress about spares. I've borrowed masts and other boat parts in the past with a promise to replace them if they get used and anything happens to them and haul all along the way. remember to have a plan for storing a mast on an empty trailer if carrying a spare mast - planning ahead also reduces stress on ground crew. I carried a pre-made 2x4 arrangement that clamped to the trailer with U-bolts and went together with carriage bolts that was assembled after the boat was unloaded. We saved the hardware and discarded the rest when packing for home. Regarding spares - Mischa demonstrated a lesson to all of us one morning with a really sketchy beach start (big waves, light wind). He put an entire rudder system on the beach behind the boat at the start line - cross bar and all - fully assembled, and ready to clip onto the boat in the event of a rudder problem. I think they used it (or loaned it to someone else that found themselves suddenly in need). That's a whole lot faster than running back to the trailer to find and replace individual pieces-parts like we all used to do.
I tried an RV once early in my Tybee campaigns (prior to the Frank and Jake era) and it was a humongous pain on the ground crew. Along with some incompatible personalities and a lack of communication in some key areas about who was staying where, it led to just enough additional stress that the crew got so mad at each other and they all left the night of the finish at Tybee. I woke up that morning to discover they left in my RV AND my truck leaving me and my wife in Tybee with no vehicle and a boat on the beach. At least they left my trailer there, lol. I gave up on the idea of RV's after that ;-). My take away from that experience is to make sure the accommodation plans are known early and upfront and handle the communication of those details personally.
Lastly - don't.forget.the.paddle. I was honored to meet Gaulden Reed on the beach one morning in Daytona - a day after we forgot a paddle and struggled to get through the surf for an eternity during a start. Gaulden, navigating a walker around the boats on the beach, shook my hand and said how he enjoyed following our team. We chatted for a bit and just before walking away said "oh, and be sure to take a paddle today". :-).