Can I use two passports to extend my stay in Thailand without a visa for nearly four months?

Good morning,

I have a little question about visa:

To escape the Grey European winter, I bought an Airlines ticket that Will let me arrive in Thaïland on thé 8th of December to come back to Europe on thé 3rd of April. ( nearly 4 months)

Now m'y question is, as I have two European passeports (Italian and French) would it be OK to arrive with no visa and get after 30 days an extension for other 30 days with thé first passeport,

then fly out to Kuala Lumpur to come back to Bkk and make thé same operation with thé second passeport to cover thé following 2 months of my stay ?

Do the police at the airport check the return date on the ticket and can, according to the delay of nearly 4 months, deny m'y access to the country ?

Would it be risky ?

Thank you very much for your kind advise !

PIETRO ( Conte Cotta)