all good advice. If you use the section of inner tube, you have to put it on when the fork is removed, or use a tube that you can stretch all the way over the fork blades and crown. I found that a tube that big wasn't a snug enough fit on my HS...YRMV. The Lizardskins job is thin neoprene "wetsuit" fabric with velcro, so it can be attached and removed with everything in place, but I also found it wasn't as tight a seal as the innertube kludge. Both of these will degrade due to grease contact, the neoprene holds up much better to grease than the butyl tube, but both are "disposable"...and the innertube is practically free.
Many conventional HS come with a small contact seal for both top and bottom, I'm servicing a Tange Levin right now that has them, but the cups/races are designed with a lip to accommodate the seals, so I don't think you can just put them on any HS.