[aerohead]

I wanted to mention that the smaller trailer has a C-Channel axle,with stub-axle hubs captured by clamps.
Narrowing the axle would be straight forward if you chose to do that.
The frame members would have to be re-drilled for the new width,depending upon how much you shrunk the dimensions.
It would allow some flexibility with respect to the axle location.
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I suppose that the receiver tow bar could be customized for a proper vertical ball position to keep the deck level.
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The 12" wheels should have a rolling resistance advantage over the 8".If you can get the 14"s on there,it would really slow down the wheel bearings.