I guess I've faced this issue many times in nearly 60 years of putting up antennas. It started in about 1957 with clandestine antennas for the crystal sets I was building when my bed-spring and second floor ground to the toilet didn't provide the DX I wanted. My dad didn't want me drilling holes in the side of our house. Living just a few hundred yards off the frozen shores of Lake Superior, he and my mom certainly didn't want me to break the integrity of our "storm windows" and inside windows, in an area that had regular gale force winds, regular -40 F degree temperatures, and lots of snow. That philosophy has followed me to this day. For about the last 40 years my wife and I have lived in rural Virginia or West Virginia. I have no desire to breach the integrity of our household weather perimeter. Over about the last 40 years, I've created many methods of bringing antenna access and safe grounding (earthing) systems into my radio rooms. I also did this professionally, on and off, during my career. My present radio room is in the basement of our West Virginia log cabin. The sills of my two side-by-side ham shack basement windows are about 6-inches above ground level. The right-side window provides connection, with a #6 AWG solid copper wire to a standard copper-clad 5/8" x 8' ground rod sunk to about 7-1/2 feet outside the window. That rod connects around the perimeter of our house to the grounds for our TV-satellite service, our Internet Service, our water well, and our electrical service. The #6 ground wire from that ground rod enters my radio room through about a 1/4-inch hole, in the bottom sash on the right side of the the right-side window. Inside, outside, and in the middle, it is sealed with electronic grade RTV. It is now a window that I don't open, except in an emergency. There are stress loops on both sides of the sash that have low-resistance/low-tensil ties between the loops (#22 soft-drawn copper wired soldered at the top of each loop). The back of my desk and equipment shelving is almost exactly 10-feet long. I have a piece of 3/4-inch copper water pipe mounted to the wall behind my desk and shelves. Everything in my radio room is connected to the ground wire mentioned above. Plus everything I have plugged into the mains is connected through the third wire on an electrical circuit that serves only my ham shack equipment. Is is safe? I've been involved in this stuff professionally for many years. I don't think anybody really knows. But ... Finally, to the antenna feed-thru possibilities. My present system uses three small holes drilled in the sash of the left-side set of windows described above. Two small holes allow me to bring two #10 brass screws through the sash, separated by 2- inches from each other. That is the spacing of my home-made ladder-line. The ladder-line connects under washers and the heads of the screws that pass through the window sash. The inside connections connect to my "ugly balun" via nuts and two brass washers on each screw from the outside. I also have about a 36-inch piece RG-213 cable through that same sash that I use for experiments. About 24 inches is inside the sash, with about 12 inches outside. Both ends have good quality weather-proof N-type connectors. These too are sealed with RTV where they go through the sash. I've also done the piece of 1x4 or 2x4 board under the sash, with holes and connectors. They work OK. For houses without the newer type of vacuum sealed double thermo-pane windows, these cases may be difficult if you have "storm windows" or external screens. Those situations may require drilling through the house walls. Anyway, just something to think about. There are no rules.