Awesome tank upgrade. Metal halides are indeed an option, though not as popular as MVBs in the US. I have no experience with them (Exo Terra is an OK company) and you could get Mega Rays at a slight discount (look for a coupon code on their Facebook page).
I have one basking area in the center of my 125G, and I think it's enough. One at each end might be a bit much, though you probably have more creative ideas than me

I also think turtles have favorite spots, so a second area might not get any use.