Wish I knew you were looking for a .15 size plane when you were here, I could have shown you a bare bones Challenger, and given you a rebuildable hulk of a Ringmaster Jr.!! The Challenger is a nicely designed model, and even with a FP or LA.15, I think you should be able to prop it for a speed you need for the line length you need. If you can get a .09 of some flavor, the Shark .15 and the SIG Akromaster could bothe probably be flown with an .09 on that line length. I have thought about a really light Akromaster with a Norvel .061 on it on 45 foot lines or so. Another one of those "one of these days" projects! In thinking about it, any of the models mentioned with a .10 on it might work on that line length, if you can find a LA.10.
Good luck with it,
Dan McEntee