Those wheels are a long way back, for balance you may end up adding a section at the back of the trailer, do you know how much you can legally overhang the back of the trailer with your boat when towing? Perhaps you could consider putting a couple of bits of steel across the trailer then putting the boat on it to see how the weight sits, you just want a bit of weight on the tongue, then it's easy to add a bit at the back for some rollers. I don't like hulls sitting on the trailer when tied down so I have beam supports, I'll try to get some pics this weekend