Didn't realise about the isolators - the external psu is a 12v one and the internal board looks like it's purely going to run from the RasPi 5V so I thought they were needed.
We would normally just glue the chip upside down onto the stripboard and then solder wires from the legs to the board - although now we have no need as we'd just get a protototype PCB made and use our "virtual" stencil printer and pick and place machine to do the hard work!
It sounds obvious, but you only need opto-isolators when you absolutely need isolation.
For example, on some boards we use then on external facing connectors (both inputs and outputs) where we can't guarantee that the end user is going to do something silly, like instead of connecting a switch they hookup live and neutral of 400V AC! In that case, it would be bad.
We also have a system which requires 2 separate 5V rails specifically to prevent current flow from one to the other, so we have to use a DC-DC convertor to create a second 5V supply and then use opto-isolators to get signals from one side the other. If we were to short the grounds in this case, then we create a common path from either of the supply rails, which in our case means that the circuit won't work.
Btw, our led driver board is here (L1):
http://www.kestrelradarsensors.com/products.phpAdrian
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