Front to back. If you don't have enough tongue weight (and you don't have a bunch of extra gear right by the back door) it's more than likely the trailer manufacturer has the axles too far forward. I think the trailer manufacturers are getting better....but if the wheels are in the center of the box portion of the trailer they are probably too far forward (trailer manufacturer might do this to compensate for a weaker frame design). Should be somewhat behind center of the box. If tongue weight is still a concern, load the lightest sled first all the way to the back door and save the heaviest sled for last with the snowflap in the nose. Easiest to unload too. I don't have any floor protection, I use slip on ski-slips instead. When I unload, provided the tracks aren't frozen SOLID, I don't have to touch the throttle. Start the sleds, idling, I just pull them out by the ski loops down the ramp, minimal effort. Depending on the size of the trailer and sleds, you can usually fit 1 more in if you "hand load" (read: try not to throw your back out) and have sleds facing opposite directions, like Legend02 above. Need at least 2, 3 people better for that, dragging sleds up the ramp backwards to get them in "nested".