That sounds like a great idea, TC. I've used a ziplock bag like a pastry bag to 'pipe' the filling in....but I think your trick sounds even better.
Here's the recipe I've used, I think I remember thinking I'd add about 1/2 cup to the sauce as it got a bit 'dry'...otherwise a big hit with everyone:
Make-Ahead Manicotti
1-15oz container Ricotta
2 large eggs
1-10oz pkg. frozen chopped spinach, thawed & well drained
1 cup (4oz) shredded mozzarella
1/2 cup grated Parmesan (divided in two)
1½ Tblsp. sugar
1/8 tsp. salt
¼ tsp. pepper
12 uncooked Manicotti shells
1-32oz jar spaghetti sauce*
> Stir together ricotta & eggs, stir in spinach & mozzarella, ¼ cup Parmesan, sugar, salt, pepper.
> Using fork or teaspoon, stuff into shells *see note below
> Spread ½ c. spaghetti sauce into bottom of greased 11” x 7” baking dish, place shells in single layer, pour remaining sauce over shells, covering completely
> Cover & chill 8 hours
> Bake, covered @ 400°F for 40 minutes
> Sprinkle with ¼ cup Parmesan & bake 15 additional minutes
> Makes 6 servings *I used Paul Newman’s or Emerill’s (sp?) Marinara
I saw a hint on tv for stuffing manicotti shells: take a gallon ziplock and fill with the stuffing mixture, clip off a corner and squeeze into one side of shell til half thru, turn and do same to other side. (Good trick for filling cupcake/muffin tins, too)