Yeah, I'd just set a larger clearance (= longer spokes) and thinner/fewer spokes. Bonus points for setting different spoke patterns on different layers so it still averages out to, say, an evenly spaced four-spoke or whatever.
There's always the option of converting* the planes to polys, which offers richer design rules and connect options (though you still only have the two or four spokes and 90 or 45 degree options), at the expense of more repour time**.
*A manual process, sadly.
**I've done a few large designs (~1000 parts, 8 layers) and the time taken to calculate plane connectivity is dismal, whole seconds after each object move. Changing to polys fixed that, but again, at the cost of repouring them (which at least can be done in batch, unlike the plane step).
Tim