You can use an older PC to record TV with. I do not yet have one in our RV and we are not Full Timers but in my house I have 2 PCs (1 in living room and 1 in bedroom) connected to my rooftop antenna that allows me to record TV.
Windows 7 comes with Windows Media Center which is how shows are recorded. Windows Media Center also has a full guide and everything. Now in order to record you'll need a TV Tuner card installed, best bet since you are looking to plug into park cable is to get a "Dual Tuner" card, 1 port will be for analog signals (Park Cable) and the other Digital signals OTA Rooftop antenna and QAM from un-encrypted digital cable.
Remember you don't need the latest and greatest PC to get this to work, he PC I'm using is almost 8 years old and works excellent. You can usually search Craigslist or eBay for HTPC and find one for around $120 to 150. Also it will need Windows Vista or 7, they removed WMC in Win 10. If you have any questions feel free to PM me.
Here's a couple of links to get you started...
Beginners Guide for Setting Up Windows 7 Media Center