It sounds like you are in early days of the startup. Having just gone through a similar the process (and now likely closing up shop), I can perhaps offer a little bit of insight.
If, as if stands, there are two co-founders working on this, you are going to be tight on resources. I imagine your co-founder is doing all the development, and you are doing all the non-technical work. (This is similar to where I was.) The challenge is that there is a lot of stuff to do. And what is perhaps less evident, the amount of stuff to do only increases. This may be okay if you are able to procure funding, and then hire people, but it is challenging when you are unable to get funding (as I was), and it killed the project.
My challenge was that our team was not well established (it was really me with an offshore dev team)...my co-founder was not working on this full time, and although I did have a design team, they were also not sufficiently focused on our project. That left me with all the heavy lifting. I suppose you will be in a similar place.
For me, I had to get the company to revenue...which I did. The problem? The more clients I got, the more work it created. I was already pushed to my limit, and the work was getting heavier and heavier. There is a great philosophy in the startup world to 'do things that don't scale'...and I believe you need to do that. But here's the catch: that works when you have a team, money, and runway. It doesn't work when you don't have any (all?) of those things. To get money (Angel/VC) I would need to sell more. It would create more work. I would had less time to raise capital. The more I pushed, the more cash I would generate, the more work I had, the less time I had to raise capital.
I know it sounds ridiculous...if I was making revenue, why didn't I just keep on pushing? The answer is that there is a pretty large (and deep) chasm that needs to be crossed. You need to be able to continue growth, and raise money. I couldn't do both. I didn't have the time. So, although we did meet a level of success, we didn't have enough...and I didn't have the time to wait for more money to come around.
How does this relate back to your conundrum? Well, I would never say that you couldn't do what is required in 4 days of work. It is possible that you can. BUT, there are two types of companies out there: unicorns, and non-unicorns. If you are a unicorn, things seem to work from the start. Growth happens organically. Revenue comes in. You meet traction head on, and your user base seems to grow with little work. If you are a non-unicorn, it is a slog. You are constantly grinding to get that next client. Each client you get needs to be serviced. Since you are a SaaS company, the amount of money likely being paid to you isn't high...you need lots of clients. It is costly (from a time perspective), and as a result you need money to hire others to help with this long ramp. Getting money is a challenge, and you sometimes end up in the vicious cycle about needing more traction to get funding...
I wish you all the luck in the world. It is a long journey, but a valuable one. I don't regret the year and a half I spent on it, even though it didn't work out. I suspect you will benefit greatly from undertaking the journey.