I did something like this with my Shangri-La 3 (2010 model).
* Sewed 15-17 inch (don't remember exact measurement) wide strip of noseeum mesh all around the lower edge.
* Mesh attaches to the stock floor with 3/4" Velcro. On the floor, the Velcro is sewn to the very top outside edge.
* The Velcro loop strip (soft) is sewn to the mesh, otherwise the Velcro hooks would stick to the mesh when the floor is removed.
* The net skirt also has a Velcro strip closure at the door zipper. There is around 12" of excess netting (excess in perimeter length) here which makes it easier to step over when the door is unzipped. I just fold up the excess and hold it together with two binder clips. I then stuff this into the only remaining hole formed by the gap in the netting where the door zipper is. I've also treated the netting with permethrin to help prevent bugs from crawling in anywhere there's a small opening in the Velcro or near the door zipper gap. It worked great on a trip this May with a moderate amount of mosquitoes in Monongahela NF, WV.
* I sewed the Velcro to the floor, cut a mating strip to length for the floor, and then bunched the netting evenly as I sewed it to the Velcro to account for the difference in perimeter length between the fly and the floor. I was rather hasty in doing this, and the result is that the netting is quite tight in places when attached. The netting Velcro strip has to be stretched as I attach it to the floor as a result. A better solution would have been to either pin it all evenly and bunched before sewing.
The stock floor weighed 18 oz (spec: 15 oz), and with Velcro, now weighs 21 oz. The stock fly weighed 24 oz, and with 2 ft Triptease guylines on the midpoint tieouts, netting, and Velcro, it now weighs 32 oz. The total weight gain from adding the netting with Velcro is approximately 10 oz.
Netting and Velcro: 10 oz
Stock floor: 18 oz
Total: 28 oz
Golite Nest: 29.5 oz (what their site specs anyway)
Other than an insignificant 1.5 oz, the only advantages this netting mod has are:
1. can use netting without floor to save weight
2. can remove floor to dig out bottom in deep snow for more room (advantage of velcro vs. sewn permanently)
3. can replace or interchange floor with a lighter one
I could make a silnylon floor, but I always coat the ground side of silnylon with a 1:4 diluted mixture of silicone caulk and mineral spirits to minimize the sledding effect when camped on sloping ground. This brings the weight of 1.3 oz/sq yd silnylon up to around 2.0 oz/sq yd. This would save around 6 oz over using the stock poly-coated floor.
It's not worth it unless you want a floorless shelter with a netting skirt, or you want to avoid spending money on the Nest. I camp in areas where a floorless shelter with a netting skirt is barely adequate bug protection, so I prefer to use a fully enclosed shelter with a floor. Also, I don't have a netting panel to cover the door. Adding that would put me over the weight of the Nest. I will probably purchase a Nest and remove the netting skirt mod.