Hey razzle!

Congrats! I love this song.

Regarding creating your lead, perhaps you can try this:

Option 1
Start with chord tone (root, third, fifth) whole notes. Then step up to half/quarter note chord tones. Then try sliding or bending up to those chord tones. Sing it to yourself and look for transitions between chords- leading notes, etc.

Option 2

Old bluegrass thing - as best as you're able (using scale notes) find the melody. Plink it out over the chord progression. Close your eyes and imagine how a vocalist may embellish it and see if you can't find those same tones.

Less is more.
Main thing is to have fun. Let us know how it goes.

'Rumble