I guess we will agree to disagree. My experience has been different than yours with GN equipment trailers and RVs up to 22k lbs. Never messed with semi trailer equipment.
The issue be discussed is simply adding suspension blocks under the springs of say a 5k Dexster axle and is nothing like the Reyco 4 system for large trailers. Apples vs oranges.
I'm familiar with structural steel weights and fabricating methods for a simple picture frame type sub frame with or without cross braces.
Of course we could over engineer with 3/8" or 1/2" wall tubing for the subframe and heavy wall tubing or pipe cross bracing but its not necessary.
Having hauled for a living I know from actual experience and I have seen what happens when someone mistakenly adds suspension blocks to raise a multi axle GN flatdeck equipment trailer. Broken U bolts were the result. The front axle on both trailer came loose at one end allowing it to swing around and under the rear axles.
This is a RV website but don't make the mistake of thinking no one knows or has any experience with the subject.
