yikes! using a hitch extension will lower your towing capacity. a dump trailer will weigh at least 1k. the
bx25 with FEL and BH can weigh over 2700lbs. The total with trailer and BX can be over 3700lbs then add in the chains, binders, etc.
Is the dump a daul axel? If so, how much does it wiegh? What's the MAX carrying wieght ? I wouldn't use the extension. You will need to upgrade the hitch on your ford and I hope you will only need to tow it occasionally locally.
Currently,
1*I am towing my BX with a S10 blazer 4.3L with 7k trailer/class4 hitch and its just enough to tow. It tows fine, but like i mentioned in past, a larger tow vehicle would be better. If this is all you have to tow with, if I were you, I would upgrade that hitch or tow your FEL and BH seperate from your BX. The BH is about less then 400lbs and FEL is about 400lbs as well.