Perhaps a stupid question, but do you think the market at Kraken is large enough to go with a trailing stop limit of 4%/3% and a volume of 2.3? Or do you think when the limit is hit, there isn't enough need on the market to fullfill such a "large" order (24h volume was about 26 BTC)?
Where did you see that number, at the moment it's about 430 btc. And if you do a limit it doesn't matter because the order stays there until it's filled.
That being said, 4% seems a little low to me. A 4% swing is a sneeze in bitcoinland. Might as well just put that order in now as it's going to be hit within 2 days anyway but probably at a worse price.