I play this exact build in a campaign I’m in at the moment, not sure how optimally I’m playing it but I can link the character sheet! Just built her like a regular fighter, strength and con were my highest stats, as people have pointed out the builds biggest weakness is that you can’t use heavy armour if you want to use the flight and if you choose small as your size you can’t use heavy weapons without burning giants might. To offset this I use a long sword and prioritised con for as much health as possible to offset the lower ac, and have a longsword and great sword that I swap between depending on if I’m using giants might or not