Why I finally caved and bought a battery tender after 3 dead Mopars

For years I thought battery tenders were for people who trailered their cars to shows and never actually drove them. I stored my 1970 Challenger in a cheap storage unit over winter and every February I'd go out there to find a dead battery. After the third time paying $140 for a jump start service because my portable pack was also dead, I broke down and bought a $45 Battery Tender Junior. I hooked it up through the cigarette lighter with an adapter, which was a dumb idea because that socket on old Mopars is not always live. Switched to direct clamps on the terminals and ran the cord under the unit door. The car fired right up after 4 months of sitting, which honestly surprised me. Now I keep it on a trickle charger even during summer if I know I won't drive it for 3 weeks. Is there a trick to mounting these units so the cord doesn't get chewed by the door seal every time you close it? That's the only part I still hate.