You can easily spend 32 days in Peru so I wouldn't try to add another country. Your itinerary depends on your interests. For example: do you want to include the Amazon? Do you like mountain trekking?
We didn't use Airbnb in Peru (but I don't see why not... we did use Airbnb in Colombia) but we had no problem finding affordable hostels and hotels.
We traveled mostly by bus and did not use Peru Hop as going by bus is easy and cheaper.
We had 30 days and didn't go the Amazon, Huaraz or Lake Titicaca. Northern Peru was great. Here is our itinerary and (very long!) trip report:
Day 1: Lima. Overnight bus to Trujillo.
Day 2: Chan Chan, overnight in Huanchaco
Day 3: Huaca de La Luna, Trujillo, overnight in Huanchaco
Day 4: bus to Chiclayo. Shared taxi to Lambayeque.
Day 5: Tucume. Lord of Sipan museum. Overnight bus to Chachapoyas.
Day 6: hiked Inca Road from Levanto to Chachapoyas
Day 7: Gocta Falls
Day 8: Kuelap
Day 9: Minibus to Leymebamba, mummies museum
Day 10: Minibus to Celendin and minibus to Cajamarca
Day 11: Inca baths and Ventanillas de Otuzco
Day 12: Cumbe Mayo and flight to Lima
Day 13: flight to Cusco and explore Cusco
Day 14: bus to Pisac (hiked to top of ruins and back), bus to Urubamba
Day 15: bus to Chinchero, shared taxi to Maras and hike from Maras to Moray and back, on to the salineras and the road to Urubamba
Day 16: bus to Ollantaytambo. Tried to hike to Inca Quarries (got lost, still a great hike)
Day 17: Ollantaytambo ruins. Shuttle to Santa Teresa. Hot springs.
Day 18: minibus to Lucmabamba, hike via Llactapata (great view of MP) and Hidroelectrica to Aguas Calientes
Day 19: walk up to MP, MP + MP Montana, walk back down to AC
Day 20: quiet morning in AC, walk back to Hidroelectrica, shuttle to Ollantaytambo
Day 21: granaries in Ollantaytambo, bus to Cusco, bus to Pisac but got off at Tambomachay and walked via Puka Pukara and Q'enqo to Sacsayhuaman. Overnight bus to Arequipa
Day 22: Arequipa
Day 23: bus to Cabanaconde
Day 24: hike down Colca Canyon to Llahuar
Day 25: hike in Colca Canyon: Llahuar to Fure to Sangalle
Day 26: hike back to Cabanaconde (walk planned for afternoon but needed a rest!)
Day 27: early bus to Cruz del Condor. Bus to Arequipa. Night bus to Ica
Day 28: Huacachina
Day 29: bus to highway near Pisco, taxi to Paracas, bike ride in Paracas Reserve
Day 30: Ballestas Islands boat tour. Bus to Lima. Flight home after midnight.
https://www.lonelyplanet.com/thorntree/forums/americas-south-america/peru/trip-report-very-long-part-1