It weighed exactly 400 lbs. That was when I was using the original 1.25" square tube axle and springs (of unknown weight rating). After much alteration, repairs (including adding a Dexter 3500 lb axle, brakes, 25.25" springs, peripheral hardware, and my own frame reinforcement/attachments, and bumpstop contrivance), camping gear and trailer additions, I figure I have it up to 1750 lbs, or so (last reasonably calculated at 1630 lbs, with any accuracy, 2.5 years ago). I can still barely lift the tongue (bad knees and back), so I'll stop there, with the changes. I inadvertently tested the durability/strength of my overbuilt frame with overbuilt 3/4" plywood cabin, when I went into a deep, wide chughole in the road, at 75 mph. My truck bounced into the air, as did the trailer (as seen in my mirror). The impact knocked everything in the bed of my truck into an unorganized mess, but upon inspection, trailer contents fared well. Trailer structure,tires, and suspension also showed no damage, but my truck tires (10 ply, E-range) suffered two broken belts. So, I travelled the last 175 miles home, bouncing all the way, at a reduced speed (major storms approaching, on a Sunday, not yet sure of what to repair). All-in-all, even if you end up building a bit too heavy, it might pay off in added durability off-road. Just get a bigger tow vehicle, if need be. I intended my trailer to be sub-1k lbs, to tow with my HHR, but ended up towing with my 2500HD (I've towed 10k lbs with it).
Holy Spiccoli! That must have been quite a chuckhole! I used to live up north, where those epic chuckholes would crop up once in a while (too often in any case). Don't see them here in SE TN. Hope I never stumble across one of those road craters. I'll keep that in mind when assembling the cabin.
I'm not too concerned about being the build being too heavy. Fifty extra pounds is good insurance, I figure. The goal to keep it under 1,500 lbs total weight though for the sake of my XJ's transmission. I certainly don't want to let the smoke out of it in the mountains.