Sounds like you have two options:
Remove bumper, replace with standard one.
Remove lowering springs, replace with standard ones.

Mine is a classic, with standard front bumper, and splitter from MRO styling. It sits on 17" wheels, is not loered, and NEVER touches bumps.

Alcazar

 

this is what some people on the vr4 site did.

take off bumper and turn upside down, and with a large piece of paper trace out outline of botom of bumper.

take drawing to local laser cutter, (my nearest one is in marlow, look in yellow pages), and have them cut it out in sheet metal(STEEL).

pop rivet this to the botom of your skirt make sure u use steel pop rivets. as ali ones rot realy quickly.

 

i work with sheet metal if you add any more onto the bottom it will scrape more

the only way sheet metal will help is to have a little turn up lip ( bit like a snow ski ) sort of thing, this will help to protect the bottom of bumper from the road, but will stress the fixing bolts when its still scapping ground, then add if it does snag on ground and the metal tries to rip away, doh the damage,

sorry to be a pain in your plans

pm me if you want any more info on the subject

simon