How about some random thoughts? Why not?
Around here, "door to door" (called "solicitation", as in "no solicitation without a permit") is against the law in almost every township. I guess file that under the ever popular park sign -- "thou shall not disturb the vegetation or turf", among other crimes against humanity. When you read those 30 bullet point parks signs in that 2 point font, they would save time and taxpayer money simply posting "thou shall not have fun here".
Me, I focus more on institutions (e.g. churches, private schools) than private yards; we have plenty of them around here, and they tend be be large and old. While technically "private property", there is no real "owner", just a responsible person, who likely, on average, will care less about the lawn and give you a yes.
Yeah, if someone knocks on my door and asks to dig holes in my yard, I'd likely say "no". Of course, I've already dug the holes myself duh (interesting side story here -- I once got permission on a small yard in an old town, and the elderly owner, who was a widow, told me her husband had a metal detector after I got the permission. Lovely. I detected it anyway, and managed to find 4 silver coins including a walker, and some silver jewelry, so you never know). I would google that one or use an AI chatbot to look for different wording. How about "there is rumored to be valuable treasure on your property, can I look for it in an extremely non-invasive manner?". Carry a dowsing rod, or some other bizarre looking wooden device, and claim not only can you locate their valuable treasure, you can teleport it into your pack without disturbing the turf. Other people seem to be claiming this.
Me, I won't allow them to sell Fuller brushes, vacuum cleaners, encyclopedias, religions, Ginzu knives (what is a Ginzu knife anyway?), or whatever else they are selling these days. What do they sell these days? Who knows, but they certainly don't have a permit, as far as I can see. Last guy who came around was selling wasp nest remediation services. I told him the wasps have a permit, and you don't. I also always tell them the wasps have COVID. That gets rid of them quite quick (the salesman, not the wasps -- they are my friends and have as much right to be here as I do, so long as we don't sting each other).
Of course, I make exceptions for neighborhood kids selling whatever it is they sell, if I recognize them. Why not give them the impression that the real world is easier than it really is, but I don't have the heart to turn little kids away, who feel they are working really hard and building self-esteem, when in fact, like many of the rest of us, they are blindly working for "the man", even at 5 years old.
Now, to use a basketball analogy, "the shot not taken never scores", so unless the cops come around because you don't have a permit, or you get stung by wasps, what is the downside? We have a cool example of this from the real world, from the world of theoritical physics -- back in the day, Richard Feynman, a famous physicist, would simply walk up to girls in a bar and say, [well, you know, lets keep this site family rated]. I know some folks who would take a 1% success rate on this, tho I'm told "think of it like baseball batting averages", .300 is your goal but refine your technique; don't just mention holes. (I've actually tried this myself, because I am a huge Feynman geek (even scientists have their fan club; scientists like Brian May of Queen get to double dip; how cool is that?), and because I am naturally curious. You learn quickly why maybe it is not such a good idea after all). Me, I'd take a 30% success rate on pretty much anything, including door knocking, as I think that varies by culture and locale.
So, as was already pointed out, style yourself appropriately, and to quote the best line, from one of the best movies of all time "Roadhouse", "be nice". As someone who has literally and truthfully been to over 2/3s of the counties in this country, this varies by location, but I guarantee you, at least around here, if you knock on doors all inked up, in cammos, or like you just walked off the set of "Duck Dynasty", you won't play here. I have nothing agaist people who style themselves thusly, or pretty much in any manner, just the reality of what won't play around here. As an aside, I was just in a town where the dude working the hotel desk styled himself with a huge swastika tat on his forearm. I didn't feel like playing there.
So, just like in almost all situations, just try to relate to the person a bit first, before asking about holes.
Well, more random than thought, I suppose, what what else are you supposed to do to break the Monday morning blues (geez, its a sobering thought to realise that 14% of our lives are Mondays). So, to actually provide something useful (maybe), people are always asking "where can I find silver". Well, I'll tell you. There is a town in NW Minnesota called "Kennedy". If you go there, you will find an old, abandoned school, I think from the 40s or 50s. If you bring an E-Trac, you will find shiny coins (at least I did). It seems to be part of a park, so no permission needed (at least I didn't seem to need any).
YMMV and good luck out there.