We don't play 2 up front though, we play 1 most of the time, so that 4th striker is unmanageable. How do you convince a top quality player to sit on the bench for the majority of the season?
If we even play 2 up front for a quarter of our games this season (I doubt we will), it's not enough to share around. It's 57 starts and about 25 sub appearances. If you assume Stewart plays 35, being our first choice (and accounting for injury), you then have 22 starts and 25 sub appearances left. Broadhead managed 20 last year and he was injury prone. Assuming he's the 3rd striker, he'd expect the same again as a minimum. That leaves the 2nd striker on 27 games.
Personally, I don't think Simms will be happy to only make 27 appearances (a lot from the bench) and Broadhead 20 (a lot from the bench). I've no idea where you fit a 4th into the mix.
Good squad management isn't about having an abundance of players in reserve, it's about maximising the available resources. Spending a transfer fee and wages on a 4th striker that won't play, plus having an unbalanced squad where people are unhappy at the lack of game time is the opposite of what we should be doing.