I usually take off one of the big hoses near the front of the van (under the spare tire area).

Have cardboard on the ground and a couple of buckets/rags handy to catch coolant (it will still be messy so wear dirty clothes).

After one hose has emptied, undo the other one, now drain it into a bucket.

THEN insert a compressor air spray nozzle into one of the hoses with a rag to fill up the gap around the nozzle.  Give er some air and the rest of the coolant will puke out of the other hose....this way you get well over 90% of the coolant out of the system.

And if you don't spill any coolant on the ground during the process you earn a gold star.