That's a big tank for a small motor. IIWY I would hold on to the hulk and test your consumption. Put in a known volume and keep a note of your hours run and distance covered. This might seem a bit loose, but I've found that it gives a VERY good indication of what your ongoing consumption will be as it takes your rig and driving style into account. After you know that, you'll be well placed to decide how you want to proceed. You might find that a pair of 12l tanks work well for you for lots of reasons...