You do not have to fight with the dealer to get a full tank of DEF and gas.!!!
The dealers are getting paid by RAM as part of the PDI (pre delivery inspection process) to you the customer.
If they give you any kind of a hard time just remind them of the PDI Process.
My 14 Jeep grand Cherokee Eco Diesel had 1/4 of DEF when I saw my Jeep for the first time, I reminded them to fill it and I had no problem.
In my manual it says the 8 gallon DEF tank should last 10K when oil changes are due.
It should be part of you the purchaser as your process before you sign your name on the dotted line and take delivery to scrutinize every inch of the new vehicle and make the dealer aware of all defects!
I usually make a list and a drawing like the( rental car companies use to note damage) and get the dealer to sign it an make a copy for myself as part of the dealer form that they use "we owe"
The Jeeps are throwing different false codes relating to DEF tank and pump their is a TSB here
for a PCM Flash.
I am sure if the jeeps are having issues the RAM's are having the same problem check for a TSB like the one above.