Just had a close look at your setup which looks like you may have a 45lt + smaller 20lt ish tank
I would of expected the bigger tank to of been more than enough for a big day out. What range are you getting with the etec as I thought they were better on fuel than my F70 that gives me a burn of at worst 3km per litre and when working with spearo's a full day on about 10-12 lt. Just an observation as you may be able to lighten up the load for a fraction more speed and gain more space.
Also your tubes look very shinny, what are you putting on them
By the way thats an awesome fun looking little setup, you cant beat these small outfits for what we do.