I don't know how to post pictures on this site. I would have it professionally done but I wanted to find the materials myself for it.
If you're not doing the job, why would you supply the materials? More efficient for the fabricator to do it: (s)he has the contacts, the discounts and the knowledge.
I was told, because of the weight of the trailer on my truck, I could bend the frame of the truck if left as a bumper pull. I find that hard to believe, but I do think it would be better on the truck if the traler was a goodseneck. I have seen trailers that have been changed over, but never a horse trailer.
If the weight is not distributed properly over the axle, then yes, you can damage your truck, but long before you damage your truck it is dangerous to haul.
Cherumbeque is right in that this is not for the uninitiated. Hand it over to be modified and certified that it meets MTO or DOT specs, that it is straight and balanced when loaded. It might be an awesome trailer, but if you're going to spend $5000 on modifying it, would it still be worth it to you? That number is just a guess, especially sight unseen, but it won't be cheap to have it done right.
To post pics, go to advanced reply and click on the paperclip. A window will pop up that will allow you to "browse" your computer to upload a picture, or you can click on the hyperlink icon (world with a chainlink) and link to photobucket or something.