Another vote for BMF. It takes some time and a "very" sharp blade but the results are better than anything else I've seen. Steve's work speaks for itself.
I find myself using liquid cement more these days, it forms a strong bond, dries fast, but you do need to scrape paint/plating. I also use a lot of Micro-clear on windshields and plated parts.
You don't need to split the coax, you would them need another modem which is what you're trying to avoid. Your router connects to a modem. Run the ethernet as Ace suggested. Btw I've worked in cable for 40 years.
This is what's scary.
I will miss the magazine, just as I miss Model Cars mag. I hope they bulk up Fine Scale in response but I'm not holding my breath.