Have you been paying into social security? If so, given your savings, I'm guessing you've paid in a fair amount. At mid-40s, that's only 22 years until social security kicks in and can really help subsidize spending. That gives you a greater safety margin for the 4% rule because you don't fully need a 30-year portfolio that survives by itself.
To give you an idea of the potential significance, in our early 40s, my wife and I have already earned enough in social security to generate $38,000 per year at age 67 even if we earn no more income going forward. While there might be some changes to social security, it is unlikely to be significantly reduced by the time we claim. Accordingly, I factor that into the analysis because it will cover most of our expected expenses starting at 67, so our investments don't have to do as much work. (I also am eligible for a moderate federal pension, so that helps as well.)
Do the math, and see if it helps your situation. It's a complicated formula, but you only have to do it once to get a good idea of the expected benefits. Good luck!