The problem with Don is that he's very situational. That was ok in the past when you had 3x RotA so you put him in your hand (along with Exiled Force) only when you needed him, but now with RotA limited the situation is different and the flaws in his character really start coming out. Here's my suggestions:
-2 Don
-1 Mole (kinda doesn't fit gadgets imo)
-1 Vortex (2 theories of thought here. 1 is you can afford to use it because of gadget card advantage. the other theory is why use up your card advantage in this way. stick to 1 for 1 effects in Gadgets.)
-1 E-Con (never run this over BoM except in decks that can use its 2nd effect more efficiently, like Monarchs)
-1 Hammer Shot (nowadays, Gadgets run too many 1900 ATK monsters...)
-1 RotA (only thing it was able to even search was Don)
-7 / +7 = 42 cards
+2 Doomcaliber (works well with Raiou and can really disrupt your opponent)
+2 Book of Moon (in Gadgets, 3 is a must!)
+1 Kycoo (or -1 Kycoo, +2 Banisher, whichever way you want)
+2 Nobleman of Crossout (works awesome when both players will probably be used 2 or 3 BoM's)