You really care that much? Are you only going to drive it when it’s warm & sunny w/ 0% chance of rain b/c you want the paint to stay shiny? If that’s the case….you got the wrong truck- it’s literally meant to get dirty, made to get dirty. Secondly, I never got this mentality w/ daily driver vehicles- hobby/toy vehicles? I get it. I wash/wax my vette & choose to drive only in nice weather, but if it were my DD, who cares if it’s in a garage or not, I can’t control the weather & guess what happens the second you drive that DD out the garage? No matter how clean it is it’s now subject to whatever Mother Nature decides to throw at ya
personally I wouldn’t sweat it, I think your money would actually be better spent on a full paint correction, PPF & professional ceramic coat- then the inevitability of getting dirty & dealing w/ the elements will be much less an issue
I had a custom built 18’x42’ attached garage built on my house 6 years ago- only the toys/tools/sports equipment etc goes in it & i leave my raptor & wifes MDX outside- if it’s pouring or during winter months when really cold/snowy I have my wife put the MDX in the garage & I back the raptor up within 6” of the door shielding the driveway from the snow to make it easier to get out in the morning- that’s as close as the Raptor gets to the garage lol, I guess sometimes I back it in if I’m loading it up & it’s pouring out
Lastly… I’d check on pre-fab steel building pricing….