I assume you’re playing HWW, as you’re saying French Africa. I think this doesn’t sound like a bad strat at all! You’re making use of your axis doctrine, using geographical advantages, and expanding as much as you can whilst making allies if possible.
I’d say the only thing to be worried about is if Germany doesn’t accept your offer of an alliance - be doubly worried if France allies with Germany. Also, if France allies with the UK, you might be at risk of invasion through France.
To be honest, there’s no perfect strategy. If this one works for you, by all means go for it! Spain isn’t the best country in HWW, but it can be taken advantage of.