You'll likely get a range of answers, but the two things to watch are,,
Tow capacity, You said 7500, so loaded weight 10% under that would be my suggestion. say 6500 to 6750.
Cargo cap, Rams can run low but if for example he gets a trailer with a 6500 GVWR, allow 15% of that to be tongue weight, or just under 1000lbs.
Then he needs to consider what else he wants to load in the truck, if for example he wants a dirt bike and portable genny, they along with the tongue weight will add up quick.
Happy motorin