I wouldn't sweat altering a new guitar. It's the buyers choice and he or she should know that altering a guitar will effect its value one way or another. If I thought I could suggest a less invasive and better sounding solution then I'd try to send a message through the referring company. Then again, the owner may be a working musician and this may be their tool of choice.
Guitars, on average, depreciate until they become vintage instruments. This guitar, once altered may depreciate faster at first then appreciate slower after if becomes collectable. Then again, there may be a future buyer out there looking for modded vintage guitar.
Firstly, I don't view this question as one of ethics: that would infer that installing pre-amps in the side of instruments was <morally or philosophically wrong>. This is not the case as the major makers of both expensive and inexpensive and beautiful and not so beautiful instruments have been installing these systems for ions and are likely to continue to do so. So the installation of a pre-amp in this manner is not morally or philosophically wrong.
Badly executing the job, is however , very wrong and the manufacturers installation guide and tech sheets are a mandatory "tick" here.
Secondly, the D35 is not an instrument that is about to go rare anytime soon and neither is it particularly expensive. Any loss of long term value is likely to be insignificant when the numbers made vs time in service are taken into account. It also belongs to someone else who, as a customer, has chosen to configure his tool of trade.
We are not talking about cutting holes in coffee tables here or repainting the Mona Lisa - we are simply determining the best way to install a component for a customer who requires and contracts to have a job done. The custom car dudes have been hacking up 57 Chevs for as long as I can remember and concomitantly hack up 2012 Camaros with no moral or ethical dramas. Nobody bats an eyelid except the lock-em-away and don't use em collectors who's main focus is generally money, not performance. This is aside from the genuine and passionate individuals who collect original items to maintain for posterity which is something to be applauded.
My understanding of the Trades tells me that technicians can advise if there is a better way or a better performing alternative system but after that should park their prejudices and personal preferences at the door to their workshop and either take the job or politely decline it without comment or judgement.
Why are all of these old threads being reopened? This one is almost 4 1/2 years old and I seriously doubt that it is still relevant to the OP. The OP hasn't had a presence on this forum for over a year & a half.
I encourage all of us to officially "close" our discussions when they've run their useful course.
This was just a general question and was directed at no specific person or post. There's been a plethora of old post activity of late.
As the OP, you should see an "options" box or something similar on the 1st page of your post. Click it & you'll get a drop down menu that will allow you to close the discussion.
It's just that things/procedures/techniques change so rapidly nowadays that timeliness is an extremely relevant factor in our responses.
Rusty's response was great and worth the 'rehash', so there is a silver lining(:
Take care man (: