I can tell you from experience to go back to the client and plead with them to allow you to add copy to homepage.
I have a client just like this – he’s a high end home painter. Only has a big image, and links to internal pages on his home page. No text.
To get him ranked for the most important phrases has been an uphill battle for 3 years! I finally hit bottom of page 1 for some of those phrases because Google insists on attempting to rank the home page for those phrases even though I have internal pages well optimized for them.
And every so often what happens is Google relents and begins to rank those internal pages, and they start to move up, but then there’s an algo update or something comes along and BAM we’re back to the home page, but instead of being near page 1 we’re back to page 4 or 5 and have to struggle to get back to page 2 and 1.
I’ve approached him repeatedly about changing this but he still won’t go for it. He’s more concerned with the appearance of his site than top of page rankings. I guess he can afford that since his clients are generally very wealthy?? But it is frustrating for me because I want all my clients to rank well.
So as long as they understand 100% that they probably won’t get the rankings they want, and are OK with that, then leave as is. But I’d suggest you get that agreement in writing so that when they call you on it (because they will) you can refer back to the email that warns them that having no content on the home page will result in them not able to achieve their ranking goals.