It wouldn't be silnylon, so a sealer for polyurethane coated nylon would be appropriate, like Seam Grip. There's also a product called Tent Sure (from McNett, I believe) that works well, and can be used to coat or recoat large areas, like the floor. You have to be sure to remove all the old flaking coating, though. I've done it with alcohol and a small, stiff brush.
I haven't used the iron-on seam tape, but it apparently works pretty well if applied properly.
In any case, it's a considerable amount of work, and debatable whether it's worth it, since newer tents are much lighter. I think the Night Lite is close to six pounds.
Always remember that you are absolutely unique, just like everybody else. -Margaret Mead