You will surprised to know how hard some rims are, is easier to dent an steel rim than a good aluminum one, that's the reason I doubt that your rim will crack soon, never seen them to crack at that side of the rim to be honest with you.

Putty will work if you want to smooth the surface, not a bad idea.

Did you hit a nail or something? Many years ago saw a wheel a wheel impaled with a nail, side to side of the rim.

ps: aluminum tape, like 3 or 4 pieces, then tape and then plastic rim tape.