I used marine bilge hose. My drain was 11/4” spa hose, had kinked and cracked due to Tiffin installation not allowing room to flex.
The bilge hose is very flexible, however it is ribbed, with smooth areas every 2’ for ease of connecting
2013 Tiffin Allegro Open Road RED 34QFA
2018 Jeep Wrangler Unlimited JL
Rad City E-Bikes and Kayaks