Best way of filling in hole in wall panel behind shower unit?

[Danno1800]

Hi, I have fitted a shower wall panel and not sure what to do with the hole in it before the shower gets fitted on top. It's tanked underneath so I can extend that to the pipe and wire more thoroughly but obviously I don't want water to run down between the tanked wall and panel. Since shower units are not supposed to be siliconed water can drip down the back of the wall. How should I fit in the gap in the panel, small cuts of panel with silicone all around them or something else?

Also, when screwing the shower unit to the wall (I know electrical part needs to be fitted by someone competent) what do I do about the holes for the rawlplugs, I was thinking of squirting silicone in them before putting in the screws.

Cheers, D

 

[foxhole]

Why is the hole so large ? Plugs not required in a shower panel .

 

[Danno1800]

It's that big because of the elbow joint and cable placement. The pipe is soldered and I didn't want to mess with it. Plugs probably aren't necessary in the PVC panel but the screws will extend further into the wall so I thought wall plugs might make sense. I also expect the shower enclosure screws would need them too.