Once you determine what is comfortable, you can just look at how much closer your landing gear gets to the ground. With the suspension I have on my 2500HD it doesn't seem like I can too much tongue weight. We have been cleaning up our truck yard and my scrap trailer starts out on a block, but it usually slips off the block and I wind up lifting it with a fork lift. Not long ago I had over 12,000 in brake drums on the trailer with them triple stacked in front. It was heavy because I had to twist my chains to keep them from dragging the ground, but it handled just like usual.
