There are a couple of Smart Phone apps, epically if it's a 'droid, that will tell you most of what you are looking for when it comes to Wal*Marts and such.
RV parky and RV parks locaters are two.
Several big-lot places offer overnight RV parking IF.. The law allows.. Alas some cases city, county or state law prohibits (NE for example (Nebraska) also Clark County, NV. (That's Nevada, Including Las Vegas).
These include Casinos (Who got an exception in Clark County), Flying-J, Wal*Mart, Cracker Barrell. many CW's and Cabellas, and other "Big outdoor store" most outlet malls and even many state rest stops (Freeway rest stops) though if you park there sometimes the truckers object. ANd note, MANY does not mean ALL by a long shot.
Some states even have dump stations in their rest areas.
Some of the companies that usually offer overnight will have map overlays you can download from their web site (I think Flying-J does) or apps that help you locate them.
ALso the discovery owner's group has a set of map overlays for most popular mapping software... You will have to google it: Discovery owners map overlays
Should do it.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times