OP - If your final decision is to still order the F250 it would be very wise to order the Camper Package. It will give you the same spring pack as the F350 with a rear stabilizer bar. It doesn't change your GVWR but does give you the stronger springs.
Also keep in mind the published payload of 3250 will probably end up being under 3000 by the time you get it. The 3250 is for an XL model with not one option. The weight of each of the XLT options will be deducted from the 3250. It's surprising how quickly it gets reduced.
S