Even without bush skills, people can live in complete seclusion. For example, Cook County, Illinois (land area 1,640 sq. mi.) has about 106 sq. mi. of forest preserve (not counting community parks, there are no State or Federal parks in Cook County). Roughly 15% of the Chicago area is undeveloped forest and prairie land, owned by various government bodies, utilities, and some private parties. There are half-mile wide protected corridors running along the county's two major rivers, the Des Plains River, and the Chicago River. There is also a series of continuous preserves running on the western edge of the county along Spring and Poplar Creeks, and another corridor along Salt Creek.
Just to give you an idea of how "remote" these preserves are, there have been quite a few incidents of Mexican drug gangs setting up manned and irrigated pot grows in the preserves, complete with irrigation tubing, generators, and pumps. Some of these have operated unnoticed for years.
Now to blow your mind; when I have found evidence of bigfoot activity, it is often within yards of human trails, in those preserves. I don't think all of the bigfoots retreat into the deep woods during the day either. I think they post sentries at the trail heads, watching for any humans that might go down a trail toward the family retreat. They stay watchful and mobile.
Cook County is probably the most developed county in Illinois. There are some counties in the southern part of the State which are almost nothing but national forest and hunting leases. Illinois is about 57,900 sq. mi., and probably half of it could be considered prime bigfoot territory. More than half, if you consider forests to hide in, and dumpsters and farm fields to raid.
Illinois is the median size. The average State land area is about 71,000 sq. mi., and most of those states are very empty. For example, it takes about 3 hours to drive (on highways) across the top of Florida, and that is almost nothing but wilderness. It takes about 5 hours to drive the length of Alabama, and again, it's long tracts of nothing. Even New Jersey is a big blob of forest, intermixed with towns. It takes about an hour to drive from Philadelphia to Atlantic City (on the highway), and you don't see much, even off the highway.