A few weeks ago I floated the idea of the "mountain moose" group... We're obviously larger and lumber along at a much slower pace than the goats....
No idea what's involved in setting that up, if it's not too difficult I could do it. I'm not sure the rides would be considerably easier, but the idea would be to get riders with similar abilities.
It's not difficult at all. First start up your group and advertise it on here. Then set up your league. This is quite easy too and even if you don't quite get it right first time the league should still run reasonably successfully. You could make it so that anyone riding your league must set their weight to a minimum.