FWIW here's a test of the F250 on a Parker 2510 W/A, click here.
The W/A tested is the deep-V model (21 degree deadrise), weighs in at 5000 pounds dry, and has 173 gallons fuel, for an "as tested" weight of ~7600 pounds. At 4500 RPMs she's getting 28 MPH and 2.3 MPG ... or for Capt Kevin's info
... that translates to 12.4 GPH.
For comparison purposes, your XL cabin model is the mod+-V model hull (16 degree deadrise), weighs 5300 pounds dry, and has same 173 gallons fuel ... so you should be able to see better numbers due to the flatter running bottom, at least IMHO.
You ought to consider adding a Navman or Yam fuel computer gauge ... the are the balls
! FYI - Yummie's performance bulletins are posted here