The question is very important, the recent reports from Statista and many other sources shows that 75% from the sales is happening online, so the answer is absolutely yes. The website is absolutely important for the rental startup, here are some other points to consider, consider subscribing or collaborating with aggregators, consider outsourcing the website site management and developments. Creating a website is no big deal but continuous update is a time consuming but not impossible.
conclusion: having website for startup on rental industry is a must, outsourcing it if possible is recommended unless it can be done inhouse. you may call me for further details.