Moving to Spain and expect to pay low taxes with a 6 figure salary is like going to a favela in Rio with two gold rolexes on each arm and expect to have zero issues. Just move out of there or accept the situation, there is nothing you can you about it. Why the heck do you think everyone who can, relocates?
Only giant corporations that can do the SICAV (hedge fund) scheme or companies that have physical products that are produced in Spain, or services that are for Spanish benefits (like consulting about Spanish law etc) will stay, as they have no choice.
Spain is a great place if you make a normal salary (or whats considered normal there).︀ Otherwise be prepared to be r4ped. Do not piss their IRS off as yeah they︁ aren't great at detecting stuff but if they do, they will not leave you alone,︂ not ever. You may win (they lose 50% of the cases), but they will make︃ your life extremely miserable in the process (as that's their strategy so you settle to︄ pay before the process is carried on), and will continue to hunt you with audits︅ every year after. And even if you do win, they will appeal to a higher︆ court (they can do this up to 3 times) like they are doing with Xavi︇ Alonso, who's already won twice but that won't settle it. If the loot is big︈ enough, they will hunt down.
Stay away from Spain! Only for vacations! Or be prepared︉ to pay 50% or more, better safe than sorry. You can NOT win against those︊ people, you WILL lose one way or the other (economically, emotionally, mentally, etc) every single︋ time without exception.
Regarding your question, it will not work as you think. If you︌ create a company, for example, if you are a single shareholder, you will be taxed︍ twice. That means your company will get taxed CT of 25%, and then you will︎ personally be attributed 70% of those gains. So if the company makes eg 100k profit,️ it will pay 25% in taxes. Of the 70k remaining, 70% will be attributed to your personal income tax. This is a scandal but that's just the way it is.