Elumia wrote:I have an idea for a dropped floor in a bolt together trailer.
I'm not sure what your second diagram is showing, as I can't understand the details, but here are a couple of comments:
You will be limited on the drop to maybe a few inches, as you have to have clearance for the axle under the dropped floor - dropping just the front floor allows you to get much lower. Alternatively, you could have a hump in the dropped floor where the axle was - it would look odd, but I could see it working OK.
I think, probably, you can safely leave out all the cross-members except for the front, the rear and the one-from-front, as you've shown. But you would then have to be very sure you added back sufficient support from the floor to stop the side rails either twisting or splaying at the spring mounts - bolting the side rails to the plywood floor would probably be enough.
Please note the use of 'probably'!
Andrew