The government has limited propane tank output to something like 90k BTU. You can't get anything close to 170k BTU out of a single propane tank, so I wouldn't worry about it too much. I had the same issue -- massive burner and no way to supply it with the fuel it needs. I found what I got from a single tank was adequate for me.
You could theoretically heat the water/oil faster with more BTUs, but 90k BTU is about three times more energy than you'll get from the average "high output" burner on a gas range. So I think it's probably acceptable. The alternative would be to somehow rig two tanks in parallel but I have no idea how you'd do that.
It's been a while since I last used mine but as I recall it put out quite a roar when I cranked it up. With enough fuel pressure to get it up to 170k BTU it would sound like a jet engine with afterburners engaged.