Selling 20% out is indeed normally safe, 20% rises in a single week and not very common and rolling sold calls forward is pretty straight-foward
The question is more around the income you can expect, and that's totally dependent on the IV - today it's running pretty high for calls, a 31/12 c1200 will net you $3, but I consider that exceptional, more often than not it would be more like $1. So you could probably imagine $500 to $1500 a week if you manage it well, so maybe $50k per year if things go in your favour (I pull this number out of my rear-end, but feels about right)
Other approach, if you're prepared to risk it a bit is to study the tea-leaves and make educated guesses with lower strikes, then maybe you could flip to playing The Wheel, or would the tax hit be too great?