If nathan theory is correct a float stop could do the same job, thinking about it, if you tied your hooklink as standard and put a drennan grippa stop just above the hook, that would stop them from taking it so far down, as i haven't tried this i couldn't pass comment on how/if it would work, but the idea is there, it would ruin presentation, but the small perch near me are pretty easy to catch and will appear to take anything.
Might be worth a go...
Ryan
PS If rules allow, catch a few really really small fish and hook them through the mouth on a sz 8 or similar under a chubber float or similar and chuck it under a overhanging tree or wherever they are this normally allows you to pick up some big perch.