Looks like you have the same trailer and boat as I do so this should help.
On the two centre drop axles beams I have a 2x4 on the flat. On top of that a 2x8 with carpet spans from the rear to the front frame beams.
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Again Dave has a good point, axles were designed to carry the frame and whatever load it bears. Looking at Sailavie 1's keel bunk I see both forward and rear crossmembers are bearing load along with the axles, meaning all things being equal, there would be about 1250lbs on each. We should also consider the hull bunks(not at right angle) and what they were intended to carry. Guessing 5000lb for the total load, we're down to 833lbs each supporting member(again assuming each carries an equal share). Grab a tape measure and measure the length from the center of each support to the frame attachment(convert inches to feet) and multiply this times .5X833lb, this should give the torque(ft/lbs) applied to the frame member at the point of attachment. Now you can make a wag, whether set up as it is, whats the probability you will distort the frame enough to change the camber of any of the 4 wheels..... Another thing to consider is the c.g. of our boat in relation to the c.g. of the trailer. I've noticed that it appears our boats sit forward of the trailer c.g. Bottom line, I would love to see how these boats sat on the Loadrite trailers as they left the dealer (especially the keel bunk construction). Thanks to everyone for the replies!!