I'll second both points made by Bill above. From much personal experience parallelling large generators in a past life (Navy), you DO NOT want to have a generator online but no way to synchronize when the utility power comes on.
I believe I've seen moderatly (Profitably) priced residential grade power transfer equipment sold in kit form which is just made for this purpose. Safest way to go.
As an electrician, at my house, I might think I can get away with an outlet arrangement as you described, but I know to go yank the utility meter before I hooked up. Then there is the question of which loads to connect, etc. The generator won't run everything. This is not necessarily as easy as the home owner presumes it is.
What about grounding issues?
Just way toooo many things to go wrong. Too much risk and liability, as you have no control over the home owners actions after you're gone.
Radar
