I clean my upholstery with a Bissel Green Machine and clear water, making sure not to soak the fabric too much. For stains I take a soft brush and an auto care product called Tuff Stuff that's probably the best I have ever found for vinyl. It does great on fabric, too. Spray it on, brush it in with the brush and let it sit for several minutes. Then I use the Green Machine with only water to pull out the dirt.
Does your Hoover have rotating bristles like a shampooer? If so, I would stick to something that is essentially a vacuum like the Bissel. I'm not fond of the material Jayco used on my benches.
2006 GMC Sierra 3500, CCLB
2005 JayFlight 25RKS