I think your wife may find the stock CCT/Hard-Ball seat much more comfortable than the Magnum seat. The Magnum seat was designed for style, not function or comfort. The only difference between the CCT seat and the Hard-Ball seat is the CCT seat is heated. Your Magnum very likely already has the receptacle to plug in the CCT heated seat. As large an issue with passenger comfort is having a proper backrest. My wife always found the CCT seat so comfortable as to fall asleep. The CCT having the trunk makes for an excellent backrest for her. The one time she rode with me using the Victory passenger backrest instead of the trunk she absolutely hated it. In her opinion, the Victory passenger backrest has an awful angle to it making her lean back way too far for comfort.
A brand new Magnum/X1 seat is $416. So IMHO, your used Magnum seat would have a sell/trade value of no more than $200. YMMV. Shipping costs of selling/trading your Magnum seat would need to be considered as well. For comparison, new CCT heated seat is $716 and a new Hard-Ball seat is $467.
Having your Magnum seat reworked may also be a good option.