Since your issue is more at night than during the day (or at least you didn't say there was a problem during the day), you might want to trying taking the alpha blockers with the last meal of the day, instead of the first. Tamsulosin doesn't tend to last 24h, and by taking it later in the day, you will have a higher concentration working overnight when you have the problem. Most preparations of Tamsulosin must be taken with or just after food and not on an empty stomach, because this is how the slow release mechanism is designed to work, but check the leaflet which comes with yours. Also, be careful if you take other meds which can reduce blood pressure at the same time, such as PDE5 inhibitors (Sildenafil/Viagra, Tadalafil/Cialis), because there's a risk that taking these all together might produce a temporary drop in blood pressure which could make you faint.
I'm not expert on BPH staging, but I thought the grade was more about the resulting symptoms than the size. While larger prostates tend to generate worse symptoms, that's not always the case. (My prostate was 97cc, 3x normal size, but didn't cause any symptoms. A cystoscopy showed it generating quite a large dent into the bottom of the bladder though.)