RE: personal fav covering
When I don't wish to fiberglass, my iron-on covering material of choice is Solartex.
It covers at low temerature; can usually be applied without denting wood even without an iron sock; takes complex curves better than anything else I've used in 17 years of modeling; will not bubble-up later, if applied properly; and takes paint/masking/etc. extremely well. (Especially, when usingthe color identified as "Natural".)
It is a little heavier than Monokote, Ultracote, and similar, but is substantially stronger and more durable, as well. For example, when I've landed in the weeds, and my wing leading edge hits the stems, the flowers at the top regularly punch holes through the open bays covered by Monokote and Ultracote; but, not through my wings covered with Solartex. In my opinion, the minor penalty in weight is well more than made up for with all its other attributes!