I keep thinking about the Zenoa engines, but I think even those would be too small for that weight. (
http://www.zenoah.net/ )
Here are some other giant scale planes, but lower weight:
http://www.rchobbies.org/giant-scale.htm
(they're mostly racing planes)
Otherwise I gotta side with Hal-9000 here; at 3m wingspam, it better be moving quick, if it's going to hold 90 lbs at any kind of altitude. I'd concentrate on shaving weight like your life depends on it.
Can't advise you on the electronics, but recognition is a field of its own.