I can't recommend anything like what spr352 did because of liability issues but it sounds like a good idea ...  It would depend on how the data plate is put on, but if I were to remove a riveted data plate I'd try carefully using a cut off wheel on a 4" grinder to cut the rivets.  Do not get into the tank with the wheel and do not try and remove the rivets.  If you find deep pitting under the data plate you are going to be very disappointed.  I forget now how much is allowable but it isn't much.

Another DO NOT is do not weld on the tank.  A lot of newer tanks have the data plate raised off the tank a 1/4 or so.  This is a great idea they should have done 50 years ago.  It would be nice to reinstall it that way but you would need to be a certified tank welder and the tank would need purged

ccjersey said something about drive rivets.  NO!  DO NOT UNDER ANY CIRCUMSTANCES DRILL A HOLE FOR A DRIVE RIVET!

Oh, and F2036 said "some suppliers may not fill your tank if it doesn't have a good data plate attached that can be read."  NO supplier is supposed to without a legible data plate. If they do I'd be a bit cautious because they are intentionally violating national fire codes.