In my area, skirting on "manufactured housing" - of the kinds usually impled - is definitely NOT JUST FOR DECORATION.

It doesn't require tremendous structural integrity of the skirting to significantly reduce wind penetration beneath the structure, and in a high wind "pumping up" the under-space can flip the structure off the foundation. Even rather crude, and apparently flimsy, skirting can be fairly effective; and skirting that properly closes off the "crawl space" against wind penetration is essential.

The smaller "manufactured houses" here are also required to have "tie-downs" in addition to any attachment to the usual pier/post supports. In the crudest form, seen on some "trailer house" installations, this may be a couple of steel straps draped over the top of the structure, with each strap anchored on both ends to "screwed in" anchors ("dirt augers" that are screwed at least three feet deep into the soil). More sophisticated (and better looking) methods are more commonly used, and the "strap" method is prohibited for "aesthetic reasons" in many places.

Local building codes, sometimes including special requirements for your kind of structure, may be useful. Consulting with a dealer/installer who currently handles new installations of structures like yours is likely to get the most useful information.

In my area, the term "manufactured housing" also includes full-featured structures that use "hurricane clips" at all the structural joints, are placed and anchored on full foundations, and once installed are indistinguishable from "site-built" homes. I presume however that yours is not of this kind.

There's sufficient variation in conditions and codes that you need local advice from people in your specific area.

John