Do you know if it is possible to go directly to the detail page in LSM, instead of starting with the Thumbnails page?
The thumbnail page is displayed in Small Screen Mode only (and not in Large Screen Mode).
You can initially hide the thumbnail page in Small Screen Mode by setting showSmallThumbsOnLoad="FALSE".
You can also prevent users from accessing the thumbnail page by setting showSmallThumbsButton="FALSE".
You can force a particular screen mode to be used on all devices and in all browsers via the screenMode configuration option.
Also, you can disable the Splash Page by setting showSplashPage="NEVER".
Hopefully, with a combination of the above options, you will be able to have your gallery function as required.
For reference, a full list of configuration options can be found here.
For more information about screen modes, please see here.