I had good luck with putting conductive grease on the conductors and rotor to help prevent the corrosion and burning.
Do the conductors have even wear? If one side of the conductors has more wear than the other side this could mean replacing more parts than just the cap and rotor.
I had a cap & rotor last 70,000 miles on one vehicle (replaced due to corrosion) and onother last 145,000 miles (worn out).
Every 45K miles seems a little premature for the cap to wear out.
1998 Mercedes E320, 200K Miles
2001 Acura 3.2TL, 178K Miles
1992 Chevy Astro, 205K Miles