15 amp fuse replace with a breaker

My need is quite simple. I run a 400 watt inverter from a cigarette lighter plug (ya I know, I should not). So far I've only blown one breaker. Ummm that was 3 nights ago when I grabbed the wrong cord--and plug in an oil filled heater on the 600 watt setting. Fortunately I was in front of a Walmart (yes I do have a replacement in the RV but it was late and I was tired). Unfortunately they were out of 15 amp ones so I chose to buy a "kit" which was on a rack saying $12. Imagine my surprize at the till, when it came up as $34. The clerk marked it down and I decided I may as well have it. It has some sort of tester, but I'm too busy getting down the road to look at it.

I thought it may be a better solution--just as I replaced the 60 am OEM fuse with a "home brew" breaker. (It was god awful hard to solder, so I thought an "off the shelf" might be easier--and since I don't have an iron with me......)