Sure you can, why would you want to?
If there is a problem with the electric one, fix it. A mechanical one is a pain to install and then you have 20 feet of possible oil leaks.
Can't believe that would warrant a ticket but that aside, finding a manual OP gauge with that much tubing would be an issue. Actually, lots of oil pressure senders leak and will dump 60 PSI oil in the bilge quicker than you can say oh-#$@&. You could also mount a mechanical gauge right on the engine but that serves no useful purpose except for pre-trip check. It does no good if you can't see it when under way.