Aha, the devil's in the detail! ;)

I said that Rain-X can make it cloudy, not will make it cloudy. (They warn as such on the label.)

Test it on a little corner or a side window. The type of perspex on your aircraft might be one of the non-cloudy types.

It can, however, be bit of a faff to apply properly. You are meant to rub it in relatively vigorously so that it effectively penetrates the top layer of glass/perspex. If you just apply it lightly, it will be washed off in the first couple of showers (believe it or not!)

And there's me thinking newer designs don't leak, the 500s leak around the perspex pretty well , used Captain Tolleys Creeping Crack Cure (the original)starts like water then thickens to a clear flexible seal, it stopped most on the first go,when initially applied excess can be removed for about 10 minutes with damp cloth. :D
Have always used Pledge to polish the perspex, it appears to be the polish of choice for a lot of pilots in US

The best polish to use on the perspex and the rest of the helicopter is Autoglym's Super Resin polish easy to apply and get off