Tough call but like they say, its easier to ask forgiveness than beg permission. Speaking as a truck enthusiast I would say do it but speaking as a husband I would say dont stick your foot in the bear trap unless you plan on dealing with the consequences.
I talked my wife into letting me buy my '70 by telling here they arent getting any easier to find and telling her that the $$ would never come out of bill, grocery, clothes money. I also told her I could build it for $4500, which i found out was a damn lie!
