Whatever you decide, I'd suggest you check out the specs on your Ford hitch. This might be an apples to oranges thing but back in 2004 I bought a new F250 with a class 5 OEM 2 1/2" hitch. The gross trailer weight rating for the hitch was fine , but the tongue weight rating wasn't all that great when using an extension. I replaced it with a Titan hitch that actually had a somewhat lower gross trailer weight rating, but a considerably higher tongue weight rating.
*** oh, never mind - it looks like tongue weight won't be an issue - I misread . :S