The connection using thick wire is very common and usually doesn't cause a problem. The holes for the wire must fit it snug and not be so large as to break through the surface. Most of the ARFs I've seen have this done properly. Your idea has just strenghtened things up a bit.

More concern when building ARFs is the method used to cut away the covering in the area where the stabilizer is to be inserted and glued into the fuselage. If yoou use a razor or knife you must be VERY careful not to score the wood very much if at all. Most people know when they want to break sometning along a line, a score mark will make the break much easier and cleaner; you sure don't want that on your stab!! A much better way is to use a wood burning pen or pencil soldering iron to melt away the covering. You can pull this quickley across the covering without making much of a mark at alll on the wood.

Good luck with your Seagull Spacewalker. Mine fies well and really looks nice in the air.