Do you honestly think the functional air filter, rather than the rubbish that KTM designed, will actually put people off? It's a £500+ part new so I'll just remove it if you think that's the case.
Its not what I think, but what potential punters think, but IMHO / Experience:-
80% of punters don't use forums, they think that the Manufacturers know best and want to avoid a bike someone has done any significant mods to, another 10% will just say they don't want all your extras in the hope you cannot be bothered to remove them, or even try and knock you down due to the mods they say they don't want (and know you cannot easily remove) in the hope they get more for less.
If they ask their friendly local KTM dealer about these mods they will probably say they don't recommend them, there is noting wrong with the stock filter etc.
So you are trying to appeal to a small minority of potential buyers who might want your bike with your mods and admit as much, on any given week there maybe nobody looking for a bike with these mods, but you could get lucky, especially if you don't mind waiting a while for a sale as anyone thinking of buying a bike like this and doing those mods would find yours very tempting.
I am on my third Adventure - all of them have had the standard airbox and none have blown up, I think this is the experience of the vast majority of owners, and from 2015 onwards KTM did modify the airbox - not that there was anything wrong with the old design of course ;-)
To be clear I would be happy with a bike modified like this myself, good luck if you decide to sell.
I sold my S model last Autumn privately, it had 20k on it (was mint though) and I got £7300 leaving Ergo seats, crash bars and touring screen in the deal, so £7500 is probably achievable for yours, maybe a tad more, I would probably advertise at £7950 and convince anyone calling it it worth every penny and how great the mods are.
Phone a few dealers and see what they offer, add about 15% - 20% to their prices, my best guess if they would offer about £6500 and put it up at £8995 - and my other guage is removing 15%-20% from dealer prices.