packing question

how do i pack with an stp?

i'm not really interested in buying the special underwear/harnesses as they're dead expensive so i was thinking to just have it free in my boxer briefs (the tight ones, like calvin kleins). would this work and is this generally secure enough for everyday wear? or sport? idk i feel the packer has a chance of dislodging and falling. alternatively i was thinking transtape but that'd be hard to position the stp cup with. does anyone have any suggestions for packing wiht an stp without special underwear or know if my idea of having it free would work?

and more generally packing with a normal packer - what's the best way? would having it free work? or how about adhesives has anyone had experience with that? again im thinking transtape but detracts from the realism.

obv if the only way is to get special underwear thats fine but i rly dont want to wear a harness all day and i like my current underwear lol

thanks for the help!