Sensor won't help.
Is the sensor combined with a relay/ECU by the interior mirror? or is there another relay/ECU in the fuse box?
They are all the same
except for mine, oh and ChrisGixers
- if you leave it on auto setting (as opposed to turning it from Off ot Auto when it starts raining), it will be desperately slow to start. And they once it starts, if it detects rain a million miles away, it will polish the already dry screen dry as fast as it can.
If that is not what you want, you're out of luck. If it is, you'll find the system ideal.
Sorry
At present my wipers have 4 settings
Off = Off
Auto = mostly off (except when screen is dry or properly wet)
Speed 1 = Speed 1
Speed 2 = Speed 2
Mine does seem to respond OK when the rain starts, it is just useless when I need an intermittent wipe. I am forever switching off & on again to provoke a wipe.
I don't particularly want your wipers but Chris's sound ideal.......