Hello Harley,
I'll break your hypotheses down, if I may...
- a small turbojet or loww bypass turbofan here
- its a fairly low speed aircraft
- possibly even rotary wing
- that white blob is a wing tip in about the 11 o'clock position
- inclined to think its pylon mounted
- Small late 20th century biz jet
One of your hypotheses is correct... Would you like to know which one or do you prefer a mystery?