How to run hardwired applicances on an electric generator?

I have wood burning furnace that has two 3.5 amp blower motors that I will be hardwiring to a dedicated circuit. I also have a gas generator that I would like to use to power the blower motors in the event of a loss of utility power. Can I wire the feed to a junction box and have a wire with a male plug end tied into it. I would put a single pole switch between panel and junction box and another single pole switch between junction box and the male plug end. This way, only the power source that is in operation could be used. I understand there are automatic relays and generator transfer switches, but I don't need any automation or the ability to feed the rest of the house...just a simple setup to run the furnace, fridge and maybe a lamp or two. Could this same wire schematic be done with just a single 3-way switch, with one position passing current from panel to blower motor and the other position passing current from generator to blower motor?

If I understand what you're saying by, "Can I wire the feed to a junction box and have a wire with a male plug end tied into it," The possibility of the male plug being hot and unplugged would violate the electrical code.

I also don't understand the objection to automation. If the stove is hot and electricity goes off when you aren't there, is there a possibility of it overheating and causing a fire? You can use an AC relay wired to be held closed from the house power and relax to the generator side when there is no house power. When the house power goes off, the relay releases to the generator contacts (assuming the generator comes on automatically).

For a manual system I would use a 3 way switch to select the power source from "Off," "House" or "Generator." That way there is only one possible connection at a time. Manual motor switches start on page 17 of the document at the link below.

http://www.cooperindustries.com/content/dam/public/wiringdevices/literature/lit_pdf/D-Switches_Mtr%20Cntrls_ANP.pdf