So, I've found out that the factory, in the midst of testing the Rotax 915 on the Sling 4, is considering whether the parachute box needs to move back to the rearward location.  I've been told that the testing will take about 2 more weeks.

So, for now, I'm holding off on putting in the parachute.  If they do decide that it needs to move back I do have all the parts necessary for that position, so I have the option to do it.

Meanwhile, I'm rethinking all my options regarding the engine and parachute.  I do note that many builders are not installing a parachute at all, so I'm thinking about that possibility too.  Going with the 915 and parachute does add considerably to the cost of the project.