boltos installed his Penguin himself on his 22 Ft. Safari. He got the location from Andy (Inland RV). All the wiring and condensation drain hose was already there.
Perhaps boltos will reply to this, but be careful when cutting the hole in the roof. He went too deep and happened to cut the wires. So, he had to deal with first, re-splicing those back together. Getting the condensation hose (within the AC unit) routed correctly prior to placing the interior cover back on is important too. He was getting a drip from his and this was corrected by the technicians at Airstream (Jackson Center) when he had it up there in the Winter Program for some other repairs. All they did was reroute the condensation hose, which apparently was getting a kink in it when placing the interior cover back on.
As startrekker2001 said, "Airstream sells an adapter that allows the flat bottom of the Penguin to fit the curved roof of the Airstream. If you haven't gotten that, you will need it. It costs around $85."
You'll want to go ahead and get this before you start.