I would divide the pucker into either two, three or four puckers and position them over a larger area.
I would also move the puckers away from the corners.
The pucker should be oriented so that it sheds air and water to the rear of the camper to achieve a shingle affect. The pucker in the posted picture is oriented incorrectly.
This is how I would do it:
Determine the size of the pucker.
Mark the leading edge of the pucker.
Mark the Side Curtain where the leading edge contacts it.
Remove the Side Curtain.
Open up the pucker and measure between the two marks. This is the width of the pucker.
Divide this measurement by 2, 3, and 4.
These measurements will be referred to as Width 2, Width 3 and Width 4.
Using 3x5 cards to practice making a pucker and determine the best number of puckers to use.
Along the 5" side mark Width 2.
Fold the two marks to each other to form a pucker half as wide as the original pucker.
Repeat using Width 3 and Width 4 measurements.
Assuming there is a center back seam:
Fold the Curtain in half along the Center Back seam, inside to inside.
On the outside:
Mark Center Front.
Fold Center Front to Center Back.
Mark Center Left.
Mark Center Right.
On the camper:
Determine the perimeter.
Mark Center Front.
Mark Center Back.
Mark Center Right.
Mark Center Left.
Attach Side Curtain to camper only at Center Front and Center Rear.
Double sided tape works well for this.
Locating The Puckers:
From the picture posted it looks like the pucker is not very wide and dividing it into two puckers would be satisfactory. If not use three or four.
I would not locate the puckers on the camper front leading edge.
If locating on the right side, left side or rear side avoid the corners and windows.
Right and Left Side Puckers:
Mark Width 2 on Right Side Curtain at Curtain Right Center.
Fold curtain to form pucker and align Curtain Center Right and Camper Center Right.
Double sided tape works well for this.
Mark Width 2 on Left Side Curtain at Curtain Left Center.
Fold curtain to form pucker and align Curtain Center Left and Camper Center Left.
Rear Puckers:
On camper Rear Side mark an equal distance to the right and left of Center Rear to establish Right Rear Pucker location and Left Rear Pucker location.
On Side Curtain mark the same equal distance to the right and left of Center Rear to establish Curtain Right Rear Pucker location and Curtain Left Rear Pucker location.
Mark Width 2 at above pucker locations.
Fold curtain to form pucker and align Camper and Curtain Right Rear Pucker and Left Rear Pucker marks.
Another Way To Do It:
Remove the pucker at the Side Curtain Center Back Seam.
You said that you can't sew, but I know that you can.
Sewing is one of the first and most basic of all human activities.
A little seven year old Bagladeshi girl could do this.
Purchase a stitching awl with the hole at the point of the needle.
Read and follow the directions, practice sewing 3x5 cards together.
How To Do It:
Divide the Pucker Width in half.
Mark a line parallel to the Curtain Center Back Seam equal to this quotient. This new Center Back Seam will increase the width of the seam allowance.
If the Curtain Center Back seam allowance is stitched down, it will need to be unstitched.
Stitch new Center Back Seam.
Simple.
You can do it.
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