Possible solution: Replace that bulb with LED, get lots of light without risking the capacity of the alternator coil.
This one from Amazon would work fine, as an example.
The output from alternator coils is typically alternating current (AC), while many automotive LEDs demand direct current (DC) to work. There are some LED landscape lighting replacement bulbs (from local home center) that have the same base and will take the AC, but they tend not to be particularly bright. You can add diodes or a small bridge rectifier between the alternator leads and an automotive LED to change the AC to DC to make that work.
There are some good details in the general forum in the
Upgrading to LEDs thread. It's a bit of reading, but eventually gives you all the info you need.