As you've already figured out, the lack of travel before bottoming out is the fundamental issue. The common solution is to increase the travel, but that introduces a number of other considerations (shock travel, increased ride height, front end higher than rear, alignment/caster concerns, need for a drop bracket on front swaybar, etc.). You could look at using a different bump stop solution that is more progressive in nature, or stiffer (higher spring rate) springs at the same free height, but increasing the travel is really the best solution.
The springs you've chosen are relatively short at 15.06" free height. A common spring upgrade for this problem is the Moog CC880S, which has a free height of 16.60". Naturally, this results in your van sitting higher (assuming comparable spring rates) and provides additional travel:
Ideally you'd want to know the weight on your front axle. Since your front springs are new with a known free height and spring rate, you can measure the length of your springs with your van on level ground and calculate the weight of your van. With this information, you could then calculate the expected ride height using other springs such as the CC880S and determine the best springs for your setup. It gets a bit more complicated with progressive springs like the CC880S, but it should allow you to make a pretty good estimate of how much clearance/travel you'll end up with.
Steve's springs may very well achieve the desired result; but without knowing the free height (which can be measured) and spring rate (more difficult to measure), the only real way to know would be to install them. It may be that the additional weight of Steve's setup was compensated by a higher spring rate, which could result in a stiffer ride at the same travel/clearance. This would keep you off the bumpstops, but you may be not be happy with the resultant ride quality.