Most any upholstery shop can recover a captains chair, though it is probably not inexpensive. If you have Flexsteel brand chairs, contact a local dealer and ask if they can recommend an upholstery shop (if they do not do it themselves). http://www.flexsteel.com/find-flexsteel
Here is one custom seat cover manufacturer that might help:
www.rufftuff.com/
I don't know of anybody making aftermarket seat covers for RVs - there are too many seat models & styles and not enough market for each one. It's a custom job for each one. The generic ones at CW (or wherever) are a one-size-fits all, meaning they don't fit anything very well. Here are a couple of those:
https://accessories.lazydays.com/rv-designer-seat-cover-grip-fit-single-c793
https://www.streetsideauto.com/p/covercraft-svr1001bk/
