woah that's quite the oscar tank. it may not be necessary nor recommended to have a 12 foot long tank filling the entire wall. maybe a 10 foot long one with a foot at each end so that you can go in and do maintenance on the 3 foot deep sides, including algae scrubbing, filter hoses etc. still plenty big enough to have like 8 different oscars. not to mention moving a 12 foot tank would be a logistical nightmare.
i'm planning an identical 10x3x2 along my 12 foot wall but it will be housing a couple bigger showpiece fish - arowanas, etc. my current 6x2x2 is my oscar/SA cichlid tank.