Dealer wants to increase Tongue Wt on Blue Ox Rating

1000lbs bars should be sufficient. Even if you loaded the tt to GVWR of 7500lbs you'd be under 1k tongue weight on the high end 13 percent (but over receiver rating). 1500lbs bars would be overkill and could give a harsh, stiff ride.

Ask the dealer why they want to sell you the higher rated bars. I'd guess to get rid of overstock or it's the only one they have in stock.