For 320 meters with a voltage drop of 5% allowed you would need to run 700mcm copper or 1000mcm alum. I've found this website very helpful with this type of questions.
http://www.paigewire.com/pumpWireCalc.aspx
I suppose it goes back to where local codes have to AT LEAST meet NEC local codes can be more strict than NEC they just can't be less strict. So if they wanted too they COULD decide that 12g copper wasn't enough for 20 amp, you now have to run 10g for a 20amp circuit. How the local bureaucracy...
First question, do you have an enclosed trailer? If yes would you be willing to mount a generator either on the tongue(not recommended too much tongue weight) or cut a hole in the side of the trailer and put an rv generator in? You can typically pick up a good used low hour rv generator for...
And you wind the prize....... ERRRRR, UHHHHM, What was the prize again??? lol
On the serious side I've always had my customers jobs inspected. It reduces my liability if anything ever goes wrong. I have tried installing romex in conduit(I didn't have any singles) and it got rejected by the...
P.S. Underground you can run direct bury romex but it has to be insulated against damage where it comes up through the concrete or in conduit if it comes up outside of the building. I usually find it easier to bury conduit using sweeps be cause it give me the ability to add circuits if needed...
The short answer is no. It is not allowed by code to run romex in conduit in most states. You should run stranded wire from a spool of the appropriate grade
15a 14g
20a 12g
30a 10g
40a 8g
guess what gauge you need for 50 amp lol.