Mike
I converted a Top Gun Edge 540 to take a full cannister, its a very simmilar ARTF to the Seagull one and you may be interested in the mods: Link
http://www.rcuniverse.com/forum/m_4818397/tm.htm
Also have a look at the thread on it at Top Gun Edge 540: Link
http://www.rcuniverse.com/forum/m_4629728/tm.htm
Mike