get 4 lithium A size cells plus a 4 cell batttery pack
Use them to hook up to the 87 & 30 contacts on the relay so one wire bypasses the relay & the other wire goes through the 87 / 30 pair ( or 87a depending weather you end up with a NO or NC relay.
A std $ 2 headlamp relay will be fine.
Then use the ignition to trip the relay by hooking the 85 / 86 pair, one to ground & the other to the ignition switch.
Your camera is now totally isolated from the bikes power so it can touch anywhere without blowing the fuse.
Downside is you are limited to the capacity of the 4 batteries which should give you about 10 to 20 hours of recording so you will need a second set to be at home on the charger.
If you are doing this for a long trip, get an automotive charger for the batteries and wire that into the bikes battery so it charges while you are riding thus you should always have a fresh battery pack.
