"I need 10 70lb weights on the front! I think the wise thing to do is take the MX6 off until the loader is on. I've got plenty of mowing to do with the RFM."
If you really need to use the cutter before your loader comes in, just leave the upper link extended and lift high enough to keep the front (of the cutter) off the ground. Let the tail wheel carry some of the weight.
Unless I'm transporting in pavement, I usually do this. Even with the loader on (I always brushcut with the loader installed...has more to do with knocking the brush down ahead of me then counterweighting the cutter), towing rather then transporting seems to be easier on the tractor components as well as safer if you're driving upslope.
So, this is one option...remember, the pull-behind cutters always have the tail wheel(s) on the ground, so I see no adverse impact doing what I've described.