I can give you some super-fresh news based on my experience from... today
I came back here on the forum to check for any recent news, and I realized I missed something...
Between 2012 and 2015 I was able to get a 183 days tourist visa each time, "border hopping" for a day to chile, a week to mexico, a month to italy...
I knew things had changed, but I was still able to get here mid April with a one-way flight from Europe, but this time I only got 90 days (Schengen agreements, they told me). Just in case, I had a bus ticket to Guayaquil (Ecuador) for a date right before 183 days, but nobody asked me any proof of ticket out of the country. I was also able to get it reimbursed, even though it was cheap.
They also told me I could renew it by border hopping...
Last week I went with my Peruvian gf on vacation to Mancora, then she flew back to Lima and I took a bus from Piura to Loja (Ecuador)
When I exited Peru, the lady immigration officer charged me 4.05 soles for 1 day overstay (new rules, not anymore 1$ per day, but actually 0.1% of UIT of whatever it is - I don't understand it, please feel free to tell me what UIT is). I asked her if when I would come back in 2 days, she would give me 3 more months and she said yes. From what I had read, new law is very specific for what concerns 183 total days IN A CALENDAR YEAR.
When I came back this morning, still by bus from Loja to Piura... no go. A different lady said: you are from Italy, Italians (and other countries) are allowed only for 90 days every 183, so that basically means 3 months in, 3 months out.
"Do you work in Peru?" "No I don't, I rented a room near my gf home etc.." "Do you have a ticket out?" "No, I was not asked when I arrived and the air company allowed me to fly..."
In the end she wanted to give me 20 days more but she ended up giving me 30 days... with an official explanation in the system that I have some "trámites" to do.
So border hopping is dead, overstay fines have slightly changed, and I'll have to leave within 30 days