This is a good approach, I tried it this way at first and got good results. And yes, finding longer samples would have been very helpful. Unfortunately in my case, the recordings had to be of very specific engine models, which made finding clear, HQ samples a challenge.
Another simple way to do it, which I found on accident:
I opened a single waveform (0:04 second piece), put it into multitrack, duplicated it and put them end-to-end in the same track. So basically if you play it, it would be like hearing the sound loop twice.
Then, I took the second (duplicate) piece and overlapped with the first piece by about 1/3 length. It crossfades between the two automatically, but when inline in multitrack - tada - the volume stays constant. Then, just ripple delete the portion of the second piece that does NOT overlap.
In the end, I was left with a primary piece + 1/3 overlap which blended nicely into the next loop. It does however extend the total time of the clip due to the added fade, but that's not so important in my scenario. If you need to keep the same time for each clip, then SteveG's method is probably the best option.
Thanks for the help!