You "could" spider rig or long line troll from both ends of the boat ... but, I'm not sure about long line trolling out the back while spider rigging out the front, for the simple reason of "speed" ... or actually the lack of it (for the long liner).
Spider rigging is usually done at a slow crawl, while long line trolling is done at higher rates of speed.
For explanation purposes only : consider these speeds to be "correct" -
Spider rig: 0.2 - 0.4mph
Pushing jigs: 0.5 - 0.8mph
Long line: 0.9 - 1.5mph
Pulling cranks - 1.6 - 2.0mph
Now, that may be splitting hairs over the terminology of the methods you named, but I'm just trying to explain what my comments in the first paragraph mean.