I mean there are probably a few bits you could scrape from the lock time value but that'll also be very limited and it'll have to be a block height that has already passed...
20 bytes is what would be needed to store unique identifiers on the chain afaik so it's what you're going to have to put up with... But why you think others should download whatever junk you dump on there confuses me... Try it once or twice don't use 12+ kb of space that no one else can use for anything...
That's not really my problem to deal with. Its not that I think they should, its that I know they have no choice anyways. If the issue comes down to "Just don't do that, its not right" then its not a good argument because someone will eventually abuse that. Even worse, if what I want to do can scale it will be an application that multiple end users can take advantage of so it wouldn't even be just me. I love bitcoin but it does not progress without people testing the outer bounds of its capabilities. If it becomes a major problem like causing transaction fees to skyrocket then I guess people will have to figure out a solution to that instead of urging people to not stress test weaknesses within the system. Either way, I have something I want to do that uses bitcoin's blockchain, so I would like to see what happens for better or worse. Considering the resilient nature of bitcoin and the incredible amount of brilliant engineering that goes into bitcoin to resolve its shortcomings such as the lightning network, I figure worst case is bitcoin adapts. Best case is my use case has no significant impact.