I think whats easiest and cheapest in most every case is just planer boards. They extend farther then outriggers and if you build them your self cost under 100 bucks for a pair (or cheaper). They extend typically about 20 feet or so on each side, and you can clip 3-4 lines on each board with 5 foot spread between each. Just type in planer boards on google to find out more. They are basically just wooden planks screwed together with angled fronts that make them 'swim' to the left and right (specific to each side)
Heres an explanatory link
You want to get planer boards consisting of 3 boards at least, the 2 board planers that fold up and are plastic (like riviera) perform extremely poorly and arent worth the money. 10 inch boards should suffice, and while taking up more space, you wont be disappointed.
Here's some specs to make your own:
However, Id consider these too small to work good. I'd lengthen the dimensions a bit, and add a third board. 8 inch board width sounds good though. Adding a pole on top with a flag helps for visibility.