If you use an accumulator (which acts as a spring, I assume), you'd better have a fucking good damper in your hydraulic system. Otherwise - one more vibrating element, possible flutter, all sorts of trouble. Perhaps that's the reason why they don't do this?Since the shock load is predominant, consider using an accumulator. Here is a page with a drop down menu giving many options. http://www.parker.com/Products/EPD/EPDResu...+5%3A24%3A14+AM
Essentially, it works like the shock absorber on your car. You know what a bendy rig is. This would give you a "bendy keel".