Not exactly "Plug & Play", but there again most stuff with Harley isn't as easy as it should be. Depending on the type of connectors, it isn't always necessary to buy the high priced crimping tools shown in the manuals. I've managed quite well with a couple basic stripper/crimper universal plier tools, as long as I took my time and used a factory terminal as my visual reference. When you buy the terminals and connectors, get extra terminals to practice with. They are cheap.
After you make your own custom wiring harness and see how easy it is, you'll probably start looking for more accessories to add just so you can make up more custom harnesses. IMHO, doing it this way beats the old wire taps and splices hands down. Looks professional and tends to be more reliable as well.
Jerry
I've always used weathertite connectors for my automotive stuff. but pirated the pigtails and spliced them in to make my own stuff... in fact, that is how my light harness is setup on my fatboy... quick disconnect for everything!