If you mean the Old Chatham RV resort, it is mainly a seasonal campground, where owners rent annual sites for their trailers. I owned a trailer in an other site nearby for several years and I understand that it is fairly well run with good rules concerning camper behavior, "quiet time" and noise in general. The worse that can bother you (depending on how close you are) are the few campers that cannot live without airconditioning.
The summer campers who occupy these siters are most often retired "snowbirders" who come up for the summer from Florida and the warmer southern states. Others tend to be families with younger children or Mass locals who have owned the sites for generations. Rates for overnight campsites are expensive, which tends to keep the population older and wealthier.
If you are concerned about noise and crime, you are probably more at risk from nearby vacation rental properties or worse, accommodation for seasonal workers. Sometimes, local businesses will rent cottages and overstuff them with student and itinerant summer workers. These young people work hard at local businesses all day, but thay also like to party long, loud, and late. However, "crime" tends to be more often about disturbance of the peace rather than theft, vandalism, etc. The Cape is still a relatively safe place.
The Dennis Police is responsive and very much in tune with the needs of the community.
Ask your realtor if any properties in the vicinity are used for temporary worker accommodation. They are obliged to tell you the facts.