First question, how often do you have outages and duration? Depending on frequency and duration, I'd just put a couple of 15A extension cords through a window, etc. If it's an ongoing issue, penetrate the wall and put a WP box where you can access your genset. If you go ahead with mounting a box it's not going to be small, and will be located low so you'll have a permanent trip hazard installed. You might consider just putting a raceway thought the door to feed the extension cords through. e.g. two inch metal conduit, get a couple of plastic pipe caps to keep kritterz out, you could also stuff with insulation when not in use.
As Ron J suggested, put a permanent connection on the porch, penetrating the wall and be done. Ready for upgrades when you decide 3KW isn't adequate, just make sure the raceway is large enough. Spend the $$ once.
We get on average 2 long outages a year like maybe 4 to 10 hours. We get some brownouts, but of course this setup isn't going to help that.
That's an interesting idea about the raceway. Is that a common thing? Any particular one that's popular?
Sorry I'm not up on the terms; I don't know what a WP box is.
Also a bit off subject, but I was looking into how to keep the rain off this unit. I do have canopy over half of
the back porch. So, I've got about ten feet of roof covering and after that there's about another ten feet of screened in roof. I have noticed when I bbq, the smoke tends to gather under the canopy because there's a cement block lip, one block high that I think causes that to occur and even with the ceiling fan on, it just tends to swirl around inside that area. Turning on the fan actually makes it worse. In addition, the manual for this unit says not to run it in such a spot as CO will gather there. So, I thought I'd better run the unit out in the screened roof area and was looking into solutions. I saw those tent thingys but they are incredibly expensive for what they are. So, here's what I was considering. Our dishwasher just died and if I enlarge the hole in the bottom (washer lying on it's back), the unit will fit in there. The door can be opened to pull the start cord and the exhaust will go out the back. Since the dishwasher is essentially water proof, I know that will work. Question is whether it's too confined of an area. Would I need to cut additional vent holes other than the big hole where the exhaust will be pointed out? Yep, you might be a redneck if....