That is a fine lens and the answer to your question is no, you're definitely not asking too much of that lens. It never hurts to check that the ground glass is in register. With the back off the camera place a straight edge across from side to side and then with a 6 inch rule measure distance ground glass is away from your known surface that the straight edge is resting on, then take a film holder with a piece of film that's no good and put it in where it goes. The measurement to the film plane has to be exactly the same as it was to the ground glass surface or you'll never get a sharp image.

What the others have said about focus is correct. Here's how I do it. Go out to nearest focus, probably the edge of the front overhang and put a fingernail at that spot, then roll it back so the bricks are sharp. Whatever the distance from your edge to your fingernail, roll forward half way there and lock it down. There are charts that tell you how much distance each available stop will bring into focus. Seems like 3/16 - 1/4" is where you need f45.

If it were me I'd probably focus on the bricks so they will pop and stop down to f22 1/2 and suffer whatever loss I suffer at the nearest edge. For the picture to work you need those bricks to be crisp. Those kinds of trade-offs are learned by experience and there's dis-agreement about philosophy. I'm usually wrong. But I've got a lot of satisfactory pictures anyways. Mostly the best advice is just keep slugging away.