my a/c doesn't have one and I've made 40deg banked turns on final for 9 years in it with no problems (nose down of course). I would love to know exactly how close I am to sudden death!
Two ways to do it without an AoA indicator:
1. Take the published stall speed (in the same condition wrt flaps, gear etc) and multiply by 1.09 = 1/(sqrt(tan(40 degrees))).
2. Take the above figure as a guide, add 5 knots, and fly the maneouvre at altitude. Reduce speed by 1 knot at a time and repeat until you stall.
Though stalls don't happen all at once. Unless you're flying an aerobatic hotshot (like the Yak-52/54) the inner wing stalls before the outer wing. So the notion of a single stall speed is kind of a convenient fiction. But it's close enough.
Of course a stall isn't sudden death. Unless you're REALLY low (below 200 feet), just break the stall and recover. Unless you're flying a type that tends to snap (e.g. the Marchetti 260), in which case replace REALLY low with just low (below 1000 feet).