I know you've already done a lot of calculations on this (I know you too well to assume otherwise) but I've gotta say a tandem axle is gonna handle WORLDS better, especially with your somewhat lightweight tow rig. Going over dips and rollers on back highways can get a bit sketchy with that much weight on a single axle. Even with proper tongue weight they really like to porpoise on uneven roads at speed. Another nice thing with tandems, besides how the suspension stabilizes them is if you blow a tire the trailer still tows ok. With a single axle, and the weight of your amigo, I'd really hate to see a tire blow. Trailer tires also aren't exactly known for durability. My trailer probably has less than 10k miles on it and I've blown at least 4 tires now, and they were brand new with the trailer. The last one lost the entire tread layer and I unknowingly drove it that way for over 100 miles on the way to Globe.

I'd do something similar to what wayne did with his buggy trailer, except make the deck a little taller for easier drive over the axles. His trailer is light enough to push around the parking lot by myself, and handles like a dream, even behind his mini-van.

Dallas