I would like to see whoever wrote up this rule and insists on strictly enforcing it forced to stay in a room where the temperature is -50 o dresses as the "sisters" are supposed to be dressed. No protection from about 2" below the knees, no high boots, having a fan to blow cold air up the skirt, having to work all the time, and see how long they can tolerate those conditions before realizing it is just too much to ask. If they still do not want to change, they should be forced to work in a skirt that is just below the knees with frigid temperatures and a stiff breeze going, all the time. And I do not want to hear about cross-dressing: This is about teaching them a lesson, not starting a new fashion.
Even in more moderate weather, pants should be acceptable. If you live where bugs are a common nuisance, pants offer more protection than a skirt. Mosquito bites are more common when "sisters" have most of their legs exposed (to a mosquito, the skirt is no barrier). And, wait until a bee gets under a skirt. This is far less likely to happen if pants are worn. Additionally, pants offer a measure of protection against brush, dirt, and other nuisances that could irritate someone.
Now, the same could be said during hot weather about men in suits. In places where the sweat box is mandatory at all times, going out in field circus when it is 100 o and muggy is miserable. Even in more moderate weather, different people have different tolerances for heat and cold. The important thing should be to not get so hot that one sweats--and becomes stinky in the process. This also happens when "sisters" wear nylon stockings in summer--while they might not stink, they become miserably sticky when it is hot and muggy.
All this is to hide whatever assets the "sisters" have. A fat "sister" looks as appealing as one that is fit and young when they are forced to dress this way, which is not very. Yet, the "brothers" have to visit households where worldly people (who are probably dressed more attractively) live. They then denounce close association with worldly people, leaving them stuck with these fat-looking "sisters" that might not even be fat in the first place. All to prevent people from being sexually attracted to each other when it is appropriate.
I bet they would have a cow if a "sister" were to show up at the Kingdumb Hell dressed in a L.L.Bean outfit with attractive pants. There would also be a nice ladies' shirt, and good ladies' shoes (no high heels, for comfort). Or, if I were to show up dressed in jeans and a presentable shirt and shoes that were from L.L.Beans and designed for casual-business attire (which would be of very high quality, so they would not be able to tell me that it is not in good enough condition). It would be much more comfortable in hot or cold weather--imagine if people could dress according to the actual weather and conditions. They could stay in field circus that much longer or with fewerwarm-up or cool-down breaks (plus impress the householders more with reasonableness). And, they could dress themselves to be as attractive as possible instead of looking frumpy and fat despite being fit and young.