We have a similar set up to you by the sounds of it, but no main road nearby. We have lived at the same address for over twenty years and only discovered that we had hedgehogs within the last two. Thinking about it, they only started appearing after our next door neighbour replaced a fence panel and left a large gap underneath. They now use this as a through route by coming in at one end of the garden, having their dinner and then leaving at the other; some of the boys don’t even bother with the dinner bit, but rush past the kitchen doors obviously on their way to a much more interesting destination. The house backs onto a long footpath with lots of hedges and large mature back gardens, although the one which I suspect most of the hedgehogs were coming from is now having two houses built on it; thankfully it doesn’t seem to have affected numbers.
Have you thought about asking your local rescue if your garden can be used as a release sight to boost your numbers?
So far this year we haven’t seen the frog that used to live in the plant pots outside the back doors; sadly I think he may have fallen victim to one of the cats. 🙁