I too have an RX450h+ and I had the same problem, I now wash the car in Ready mode plus any other things I do around it. I didn't go for trhe Bluetooth monitor as I have fitted a permanent connection to my 12v battery that plugs into my trickle charger, so I can just plug it in rather than relying on the crocodile clips. I have bought a USB charger (£5.99 on Amazon) that plugs into the cigar lighter, why you ask, well I'll tell you, it displays the 12v battery voltage as well. You can also see when the traction battery starts to charge the 12v as the voltage increases to over 14v. When and if the voltage drops below 12, I put it on trickle charge overnight. It's a right royal pain in the bum, not something you should have to do on a £70k car.
Mark, the other thing you should get yourself is a Noco boost to keep in the glove box, then you may have read that loads of us have bought one of these. Happy motoring!