Things like stop losses and OCO are helpful, and can be useful, but they won't replace a full API bot...there is only so much logic that it pays to put into an order type, so, you might be approaching the limit of those order types usefulness, and might want to look into some sort of automated trading strategy if your needs are growing more complex. I understand your scenario, and it might be worthwhile to look into this, but that is really more like "cancel this other order, and place another order for a dynamic amount of bitcoin", because we don't really support updating an order at the moment (I think that might change soon).

So, I would say that there is no substitute for actually just monitoring the positions yourself, but, it can be a  worthwhile tradeoff to sacrifice some those benefits for the convenience of not having to be there. One thing you could try would be to split up a big order like that into a bunch of smaller orders, where if they are linked correctly, you only have a small worry about partial fills.