At most sites, the refuge/hatchery will provide a camping pad with electric, water, and sewage hook-ups. Sometimes, there will be a "dumping site" nearby, and the RV's are expected to use their holding tanks and "dump", as needed. (Always be sure to ask for specifics before you commit). There is no charge for use of these facilities.
In some cases, there will be a "common area" provided with laundry facilities, internet access, phones, etc.
In most cases, RV's use government vehicles to accomplish their work assignments, but it's always a good idea to ask specific questions about what's provided and what's expected BEFORE you accept an RV assignment.
All RV's are covered by the Federal Tort Claims Act and by Worker's Compensation.
If specific uniforms are required, they will be provided. For example, you may be asked to wear a blue volunteer shirt with a pair of khaki or navy blue pants/shorts/skirt. The shirt will be provided; however, you'll likely need to provide your own "bottoms" at your expense. In these cases, they're likely to be common items that most folks would already have.