Add 2nd water heater for a 4+ bedroom STR?

[Matt Smith]

Do you all typically see larger properties adding a 2nd water heater or a tankless for STRs?  I'm just thinking with potentially 6-10 ppl staying there that they are going to run out of hot water pretty quickly when everyone is getting ready for dinner.  This one is in Florida so we have the benefit of warmer weather but I just can't see one 40gallon water heater being enough and am worried about getting a bad review because of this.  

Is it worth it to add a 2nd water heater before listing on AirBNB?  The existing one is a 40gal and only a few years old so it's not really time to replace it.