I'll have to agree with most - A power sunroof... not the best of ideas. You can do it, but most likely it will leak depending on how it is done. - I am not a fan in the least of aftermarket installs on cars... much less on a bus.
My Scenic has non-moving sunroofs that are stock. I have 4 total. 1 on the lower level and 3 on the upper level. They are all cracked.
They are all the dual pane. Solid glass that does not move you will have better luck with. Moving sunroofs... your in for a big challenge. Heat is an issue as well... I highly recommend adding tint to them.
They sunroof seals on my scenic do not leak, but the cracks in the glass do. Some replace the glass with a vent with a fan while others panel over them to not have to deal with the headache all together.
Back to your original question though, I have seen my share of car sunroofs leak after time. Sun and weather take their toll.
The piece about how intricate car sunroofs are is correct. I am currently replacing THE ENTIRE roof on my 2000 Ford Explorer that Had a sunroof and I wanted to retain that. (A tree fell on a portion of it and I wanted to try my hand at body work... its a fun learning experience
There are 4 drains on my explorer sunroof, one on each corner, not to mention the track and mechanical aspect of it. I have pictures if you would like to see just my roof replacement as an example.
I'm not here to tell you you can't. I myself am stubborn and will do something just despite what people say, but it will be a challenge. Your best bet if you really want the sun coming in is just a solid piece of glass or better yet, double pane.
If you really really really want to pursue this, my opinion of the best option would be to go to your local u-pull-it lot and find an automobile that has the same (or very very close to the same) Pitch and curve to the roof as yours. Then rip out the ceiling fabric to reveal the tracks, motor and gearing (along with the wiring), and drains that run down the pillars. Then cut AROUND the entire sunroof and track area and be sure to give yourself as much extra material as you can. cut everything even all the metal part of the roof that the tracks attach too and then some... basically the entire roof short of the pillars depending on vehicle.
Now I'll be honest, I'm a little naive as to what material the roof of your eagle is made of, but on my scenic it is all aluminum... so welding in steel onto the aluminum roof is NOT an option. You would have to rivet it in... and even then, you have aluminum and steel touching/rubbing rust and corrosion magnet!!... If you have a steel roof, well that makes it easier - weld the thing in... then you have the trouble of routing the drains lines, but at that point its the easier part. Just keep in mind the make, model, and year of the vehicle you got the sunroof(s) from so when you need replacement parts for seals, glass, motor, etc, you can stop by your local auto dealer and order them. Way cheaper than a whole custom job.... well it can be in some aspects.
It almost be easier to take a car that doesnt have a sunroof and use this method to add a sunroof by welding in a new roof from a junked version that did have one..... you get the idea.
If you decide to tackle this, start a build thread!! I for one want to see how you end up implementing this.