When I print with external perimeters first, the seam is more noticeable. So I set object modifiers on all of the pieces to print with one perimeter on the first layer, and added some light runners for better adhesion on some parts that were consistently giving me trouble. I typically print with 3 walls as well, and this was giving issues with some of the bridging on a few pieces. Added modifiers for those bits to print with one perimeter as well. This also maintains individual objects that you can cancel mid print in case one fails. I also added some with some I guess you can call them mouse ears, haven't tested them yet though but they should function the same as, if not better than lines alone.

Just open the project with prusa slicer and everything should import smoothly. Should be able to remove sprues/runners with some side cutters or an exacto knife. Just hold the blade against the edge and lightly wear it down at an angle to avoid stress marks.