Oh, personally I think AI will be the doom of my country. I think they're horrible and they exploit my land without actually bringing in useful capital BUT... that has nothing to do with you, or does it make me judge any guest whatsoever. It provides you with many benefits which I can't deny, lower cost being one of them
I went to the local Gold's Gym. They loan you equipment to use within the facility, but not outside. None of the athletic wear and accessory/equipment stores have a rental program... and they couldn't direct me anywhere. Talk about hitting dead ends.
I am sure you would find local rental shops near Playa Fronton, but I have not seen them in Sto Dgo.
Your best bet is to pack your gear! It isn't too heavy, right? Shoes/harness, chalkbag... You could buy a rope here.
Sorry I couldn't get a positive answer on that!! I would still love to try freeclimbing with someone at Mirador Sur, so let me know!