Then it plays out much the same. Misa gets caught and rather than spill the beans she opts to abandon her memories. Light does his Memory Gambit and then the 13-Day Rule surfaces to basically make him and Misa invincible to persecution.
Spoiler:
Rem likely kills Wright when she kills L and Watari but if not then Wright would end up working with Light since Light has no reason to kill him.
If Light starts to believe Wright will suspect him then he can just order Misa to off him through sickness or what have you.
Well with Light there really is no evidence lol.
I mean they think Penbar is special and that he investigated Light but he also investigated other people. And people died when Light could not possibly have gotten their names(or so they think). And with Misa in play they will almost certainly detain her before moving for Light. If Misa did not break under torture then she could probably survive a conversation with Wright long enough to give up her memories(since I'm working under the assumption that the Magatama works over time rather than immediately getting them to spill the beans).