If you can get full length 'guards on there, do it, they are soooo much better.
It's not so much a question of are there small enough 'guards as whether you frame has any clearance at all. In either case, get the narrowest SKS 'guards.
A great option for seatstay and fork top mounting is to use Sheldon Fender Nuts (from here: http://www.billys.co.uk/english/group.php?prod=bsis-sheldon) as they make it super easy to install/remove/adjust your 'guards without affecting the brake set up. You won't believe what a difference they make, trust me.
If there really isn't enough clearance under the seatstay brace, it is possible to cut the 'guard and, using metal brackets, attach the 'guard on each side. I can't seem to find any photos of this, but essentially you need two pieces of aluminium plate that are a sort-of 'L' shape. Attach the short leg at the seatstay brace, then they go over the brake caliper and bend down again to position the 'guard as close to the seatstay brace and tyre as possible. Not as clean looking as an intact 'guard, but very effective.
At the front, the worst case is you finish the 'guard behind the fork and accept you'll get some spray from in front. Even then, you'll still get much better coverage than from Race Blades and do a much better job of keeping your feet dry.
Does that help?