Help with pricing for a potentially large client?

Hey all! I'd love some pricing help.

I’m a freelance SMM and I’ve been approached by another marketer who was contacted by our local television and news station for SMM and content creation services. They want to revamp their presence (their current socials look a bit dated) and this would involve managing multiple brands under their brand umbrella. The marketer who reached out will handle strategy and liaise directly with the client and I’d handle the day-to-day execution.

It includes:

• Managing 5 social media accounts (4 radio stations and 1 TV station) on FB & IG.
• Providing guidance to their in-house team for posting to their news account (we’d create templates and help them with writing captions/headlines, but they’ll do most of the posting, especially the updates/breaking news)
• Creation of Canva templates for each brand
• Approximately 35 posts per week across the 5 managed accounts
• Monthly content planning call with the client
• Making a monthly content calendar based on that call and their strategy and goals
• Graphics, captions, and scheduling for all accounts
• Responding to messages and comments, with direction from the team
• Monthly report
• Some on-site content creation (like behind-the-scenes)
• Payment for a second person to work with me on these tasks

Here’s where I need some advice... this sounds like a BIG client, and I’ve worked with large ones before who ended up being overly demanding and expected posts at all hours and on weekends. Where I live, SMM is still not taken seriously and there's often a lot of scope creep with clients and I want to protect myself from that. I mentioned it to the marketer and he said that it shouldn't be a problem, but I want to set firm boundaries from now.

It sounds like a lot of work, but I would split it with the other person, and the marketer said that he would be able to help where needed. I also quite frankly need the cash as my client work is very light right now 😩 I typically work 9am to 5pm Mon-Fri, and I'd ideally like to keep it that way. I also told him that I have other clients that I plan to keep working with and I wouldn't be available all the time.

Therefore I was thinking of charging a flat rate, and then charging extra for any out-of-hours work, as well as a setup fee for creating the initial design templates. I was also thinking of having a set amount of content creation hours in the package, and anything extra would be an additional fee.

Is this the right way to go for a client like this? I've never had to price a package of this scale before.

Any feedback or advice from people who’ve managed multiple accounts for clients like this would be greatly appreciated.