My first step was to use a staple gun to attach the included Velcro along the top where there's wood underneath. Wear safety glasses
. Next, I test fit the screen at the top. Moving the center opening of the screen 4" forward of the door opening resulted in a nice taught fit over the rear side door. (The end of our bed extends about 6" forward of where the doors meet, so it also helped us get in and out more easily.)
For the rear side door, I applied the Velcro (press firmly, and leave it alone for a good 12 hours), following the curve. Note that because of the curve, the forward "offset" of the center opening is about 3" below window level, versus the 4" higher up. This may affect the length a little, too.
Do the same for the front side door. I found the Velcro stuck reasonably well to some surfaces (carpet, vinyl), but not others (plastic, "rats fur"). If you plan to remove the screens from time-to-time, you may want to explore any and all options. I used T-pins pointed downward through the Velcro and slipped between the rats fur and plastic the panels it covered in places, for example. I've only removed this edge once, and was gentle.
I ended up with about 8" excess at the top across the front door. Rather than modify the screen or spread the excess across the two doors (moving the center line back), I opted to simply fold a 4" pleat at the top and tuck it behind the end of my cab curtain rod. Looks fine to me.
Once you do a test fit, you will probably want to shorten the screens. My finished length is 60" at the center where the screens close. You may arrive at a different length. I determined this length very... um... scientifically: by folding the bottom edge up and marking with chalk. (If you're in a hurry and/or don't mind the bulk, you can simply baste that fold in place and call it good.)
I cut the excess off, which gave me some extra magnet bars from the center closure. These can be cut easily with scissors, BTW. Next, I unpicked the bindings from the original bottom edges and sewed them to the raw cut bottom screen edges, closing up one end and leaving one end open on each piece. This provided a nice casing to insert the extra magnet bar pieces into. The screen bottoms now stick nicely to the metal strips on the inside door step.
Above the front side door, we have a passenger assist handle. The top-edge Velcro runs just above that, so I cut two 1-3/4" slits through the top binding and into the screen itself a little where the handle attaches to the door. This could have been finished with seam binding, but instead, I zig-zagged the dickens out of the edges, which did the job.
Since we are in a low top van, my husband is tall, and our bed limits the space we have to get in and out, I decided to snip the screen halves apart where they are joined in the middle at the top. That allows me to detach the screen at the top and fold the front half out of the way (toward the passenger seat) if desired. I'm not entirely sure I'd do that again.
Again, we love these screens! They allow us to leave the doors or just the pop-out windows open, and go in and out without letting in all manner of flying creatures. They don't obstruct the view, have held up, and snick together reliably every time.
Hope you enjoy yours, too!