Hi,
The shipping min/max restrictions will only take into account the coupon redirection if the "include virtual product prices" setting is activated. Otherwise, only the products with a weight setup will be taken into account.
So you could set a weight in your products and make sure that this option is turned off in your shipping methods and the shipping methods will display the same regardless of whether a coupon is applied.
Note that there is also a "shipping percentage" setting in coupons. So you can also configure the coupon to give free shipping when the coupon is applied.
