Thanks for the info FarmerSid.
I build an atv trailer alot like that about 13 years ago, but used a little heavier material........I think 1.5" angle, 3/16" thick. It only has 1 cross brace (floor joist?) across the bottom in the middle.......if I did it again I would use 2 (for a total of 4 if you include the front and tail pieces). I originally used a golf cart rear-end with small boat trailer tires on it for an axle. About a year ago a neighbor told me I could have an old boat trailer, so I cut the spring shackles off, shortened the axle, and welded it under my trailer........I like it suspended much better. I am, however, interested in building another one.........and doing it better. I have had mine slam full of firewood, dirt, bricks, deer, corn, etc., and never any bending except the tongue one time. I had the trailer upside down to replace the golf cart axle with the leaf springs, and when I stood it up, I let it fall and it bent the angle that the tongue was welded to. If/when I build another I will run the tongue back to the midpoint of the trailer, instead of attaching it to the front bottom crossmember. When it bent, I bent it back and reinforced it with 1" tubing welded underneath and have had no problems since. The trailer is a real help during hunting season........we haul chainsaws and trimmers, ice chests for drinks, etc., to clear out lanes. Then use it to haul feeders and corn throughout the season, and to recover deer. It is probably the most used piece of equipment I have ever built and I can't imagine being without it. It is the same width as my atv, so if my atv can make it between 2 trees, so can the trailer. You do have to watch out for small sapplings though........if they get between the trailer and a tire, they can swat you pretty good. You really don't have to worry about that happening more than 1 good time........after that you WILL always watch out for them.
I ordered a split-fire last Friday.........I can't wait to get it in. Have you noticed less force when the cylinder retracts........in the one rented or the one you built? Was the one you built light enough on the tongue to pick up to put on a hitch? I see they don't come with a tongue jack........just a prop. Can it be moved around by hand in the woods? If mine is too heavy on the tongue I may extend the tongue, possibly make the tongue removable for easier storage.
Waylan