That's a great looking plane...[8D]....just don't forget to draw in the foam padded RX, battery, servos and fuel tank..
....I have used 150 mah packs, but they are scary, it seems like they discharge too fast. I had to build a 5 port 15 mah charger to keep a fleet of those little packs ready, plus they are too small to field charge. 300 mah NIMHs are so much easier to live with, and I think it is worth it to design this size battery into the plane. To save weight and get good fuel delivery, I run latex bladders in a compartment [below the header], that is sealed off from the rest of the gear. Another little tip, to support the pipe at the end, all you need is a hunk of latex tubing, CA it to your plane, then slip the stinger in and you're done. CA glues latex even better than fingers.
Once you get all your gear drawn in, you will see that it is doable, but not easy to keep it all in a streamlined package.