It would help if we knew the exact model SLX.
Mine (195RB) has one "low point drain" more or less right under the tank. It takes a long time as there is no pressure and not a very big opening. Yours could be worse if there is a pinched hose.
I can also drain using the hot and cold winterizing drains adjacent to the hot water heater and pump but that would take forever and probably not get it all the way drained anyway.
2017 SLX 195RB
2021 Jeep Grand Cherokee Summit L 5.7L V8
Andersen WDH hitch, Renogy 100 AH Lithium &
200 Watts solar panels from Renogy
Prev. '14 Jeep Grand Cherokee Overland, gas 3.6 V6