It is not a good idea to prolong emptying any of the tanks for any periods especially the black tank .
The scum in the gray tanks and the solids (particularly the paper) in the black tanks will hang up on the probes and will cease to operate.
The liquid will evaporate and the solids will solidify promising to create a big problem.
The movie .."RV" comes to mind staring Robin Williams.
Question: by any chance was this posting a 'spoof ' ?
So in closing... "Dump it" if you have a chance ...and
......"rinse like you mean it " !
'07 WildCat 30 RLBS ~ West Coast Edition ~
Trail Air - Tri Glide Pin Box
2000 F350 DRW 7.3 Diesel Lariat 89k miles
Edge programmer, 4" SS exhaust turbo/back
Vancouver Island, B.C., Canada