I'd go one of two ways:
Either a 1-6 or 1-8x Primary Arms ACSS scope with 45 degree irons (MBUS PRO are excellent), you could accomplish this for $500-600. This is much better at range and helps to positively identify targets that you can't with your naked eye, but a little slower up close.
Or a red dot (your PRO is fine, I've switched to a Trijicon MRO, Holosun/Sig Romeo optics are also very reliable and a Holosun with the ACSS reticle gives you BDC for extended range) and flip-to-side magnifier (Vortex 3x is quality and affordable). With the red dot plus 3x you give up a little optical quality at range for the fastest sight acquisition up close (which is when it matters most and is most likely what we would experience in a defenive encounter).
Either a 1-6 or 1-8x Primary Arms ACSS scope with 45 degree irons (MBUS PRO are excellent), you could accomplish this for $500-600. This is much better at range and helps to positively identify targets that you can't with your naked eye, but a little slower up close.
Or a red dot (your PRO is fine, I've switched to a Trijicon MRO, Holosun/Sig Romeo optics are also very reliable and a Holosun with the ACSS reticle gives you BDC for extended range) and flip-to-side magnifier (Vortex 3x is quality and affordable). With the red dot plus 3x you give up a little optical quality at range for the fastest sight acquisition up close (which is when it matters most and is most likely what we would experience in a defenive encounter).