Hi Chris
I was in the same predicament when I brought my Alphard last year.
Halfords and euro carparts kept sending me the wrong wipers.
The only place I could get the right ones were from Opie Oils.
I brought oil, filters and gearbox oil from them too.
https://www.opieoils.co.uk
As for the rear wiper. I just switched the wipper on and then switched the engine off when it got to the bottom. It returns back to its original position when you switch the engine back on.
I have seen someone pull it down manually too but I wouldn't recommend that.
Hope this helps ππΌ