Nothing has ever worked except solid fencing. I say solid, cause if it looks like it is meant to 'lean on', people will. Signs work ONLY in the daytime in the weeks before 10/31. By the actual evening kids racing from yard to yard, will never even see the sign, much less read and adhere to it.
Swayed ropes, flourescent tape, streamers, etc - every year someone would crawl over or under. Usually to take pictures. As others have suggested, I hope to have a dedciated 'picture taking area and facade' for folks to use this year.
I also started using a very bright (tactical like) flashlight. I strobe it a few times to anyone whos gets too close or is running/pushing. It is surprising effective.
My yard is a 100% minefield of cords, cables, and danger.
Oh an another note, don't make a habit of walking thru yourself (or your own family). It is one of those areas where not leading by example will give creedence to someone else to 'feel free' to stroll thru the minefield. Shouldn't have to be this way, but people are often sheep.
The rolls of construction fencing (white is better looking than orange) is pretty cheap and very effective. Split a roll in two and have a 2' high fence for side areas or walk ways. Then higher solid fencing for high traffic areas or a place where you don't want them to be able to reach as far into the display.