You might want to take a look at McMaster Carr field attachable multipole connectors. These are keyed, threaded connectors. The 0.3ââ"šÂ¬Ã‚ face ones are rated for to 4 amps at up to 250 VAC, the 0.55ââ"šÂ¬Ã‚ ones take up to 13 amps at 600 VAC. They have a good rating against water intrusion.
0.3ââ"šÂ¬Ã‚ 4-pole -> 7209K41 (male); 7209K43 (female)
0.55ââ"šÂ¬Ã‚ 3-pole -> 7152K71 (male); 7152K62 (female)
McMaster-Carr catalog pages 721, 722, 723.
These are called "micro" and "mini" connectors, but they are still fairly bulky. I donââ"šÂ¬Ã¢"žÂ¢t know if theyââ"šÂ¬Ã¢"žÂ¢ll take the ignitor voltage without arching between pins, though. I think that they would be OK. Another consideration is the metal parts exposed to the humid/salty air, the website doesn't say if they are all SS.