I'm not getting into regulations and what not as I'm not sure what they are in your area. But yes, make sure all is well on your end in terms of protection from doing the job for the client based on your local permit processes. Billboards are hard to get in our area...
We have a client that has some smaller billboard structures that have multiple ACM panels on the front for the face of the billboard. We then installed the Ackland Media Frames. We then installed 13oz banners on each of them. The client loved it and it cuts his cost way down in the future for new Ads. It lead to putting up some very large banners at a local University for their basketball stadium. We now have them all over the University for their Academic and Athletic programs. They are very easy to update in the future!
We love the Ackland Media Frames and that outfit is a pleasure to work with on projects. The banners have great tension using their patented system that requires only a trimmed banner to the exact size of the frame. No grommets, no hems.... just the banner printed to scale that you need. Just talking about it makes me want to sell more of them..lol. [HASHTAG]#MoneyMaker[/HASHTAG]
You can see an example here...
https://www.ballparksigns.com/wall-banner-frame-display/
Good luck with your project.