I've got my widow done up over kill but what I have is a normal window shade hung to look normal from outside, then over that I have a black out curtain then over that I have a piece of black and white poly cut larger than the widow and that is taped to the wall using masking tape. Masking tape works pretty well, it holds good and doesnt leave sticky residue.
But if you already have sticky residue you can use this stuff called Goo Gone to get it off. You can get it at walmart, or the grocery store or even home depot.
I've got my widow done up over kill but what I have is a normal window shade hung to look normal from outside, then over that I have a black out curtain then over that I have a piece of black and white poly cut larger than the widow and that is taped to the wall using masking tape. Masking tape works pretty well, it holds good and doesnt leave sticky residue.
But if you already have sticky residue you can use this stuff called Goo Gone to get it off. You can get it at walmart, or the grocery store or even home depot.
I realize this probably won't be exactly what you were looking for suggestion wise; however, if it was me, I would first put up blinds and then either black construction plastic or a tarp on the 'inside' of the blinds; so that from outside, you just see blinds, not a tarp or black construction plastic, which I feel might be 'brow raising'. 
You can get some inexpensive sets of blinds at the De'pot, for $30. max. And I would probably use a staple gun, or teeny nails, to tack the plastic/tarp to the small, raised "lip" on the outer edge of the molding around the window, OR to the frame around the window, if you don't have molding.
You are very wise to steer away from the velcro; that sticky stuff really is a PITA to remove!
(I've been faced with that very challenge, after removing my kitty window benches, that velcro to the window cill...I used a ton of 'Goo Gone' and a scrapper.)
If it wasn't so difficult to get off, it would be a great option...
I hope, (although I doubt), that this is at least mildly helpful!
Best wishes for frequent, frosty and bountiful harvests!
EDIT: well I see I'm a pokey poster!!
+1 for GooGone!! That shit will remove years of caked adhesive. This stuff is crazy!!!I've got my widow done up over kill but what I have is a normal window shade hung to look normal from outside, then over that I have a black out curtain then over that I have a piece of black and white poly cut larger than the widow and that is taped to the wall using masking tape. Masking tape works pretty well, it holds good and doesnt leave sticky residue.
But if you already have sticky residue you can use this stuff called Goo Gone to get it off. You can get it at walmart, or the grocery store or even home depot.
