Can you look at my pricing for proposal to city municipal's portal makeover?

I'm writing a proposal for a bid to get a contract for a city's web portal re-design. It's a multi-year contract. This is my first time doing a bid in my life! :D

They want full blown CMS features, plus some image/video upload. About 10~20 different page formats. Their original website is ASP.NET on IIS server.

My plan is to use a headless CMS where we get the CMS features out of the box. Mainly because I do not want to work with Wordpress, nor do I have the time to learn PHP. Then, I can use Elixir to build out the portal's look and feel. I chose Elixir because I'm fastest with it. I'm going to be the sole developer, and plan on doing it after work hours.

Time to launch is 6 months. I gave first two years of active development/design, and next 3 years is going to be maintenance mode.

Here's my pricing:
Year 1: $80,000
Year 2: $80,000
Year 3: $45,000
Year 4: $45,000
Year 5: $45,000
Total: $295,000

I have no idea if this is high or low. I just added 50% margin to SaaS cost + my time + design outsourcing cost.

They already have 30+ bids so mine won't probably win it, but I'm just doing it mainly for the experience of writing one.

Question: is my pricing off? Typically how would be the pricing for a project like this?

Thanks is advance!