Perhaps using gift wrapping tissue paper applied with white glue might smooth out the surface without adding too much weight.
I'm going with 1/4 oz fiberglass on my current big build and it's really very lightweight - I've just had to learn to use a gift card to really squeeze out the epoxy so the weave is showing through. But it does require a pretty flat surface to start with. And it's not too expensive on eBay https://www.ebay.com/itm/272878069574
I'm going with 1/4 oz fiberglass on my current big build and it's really very lightweight - I've just had to learn to use a gift card to really squeeze out the epoxy so the weave is showing through. But it does require a pretty flat surface to start with. And it's not too expensive on eBay https://www.ebay.com/itm/272878069574