If you run the same type of coolant in your engine and your AWIC system they could share the license plate door burp tank.
I really don't think heat soaking will be a big deal. Yes, the water in the WAIC will get to engine compartment temp, but as soon as the system kicks on, it'll cool the system. The WAIC won't care if the warm water came from engine compartment heat or heat from charge compression.After sitting for a while, by the time you're at the point where you need max power, you should be a-ok.
...BTW your Bieber avatar is awesome.-Malone