Will permanent All-on-4 be as bulky as the temporaries are?

The location of the implants is set, there won't be a change there.  The final restoration will be very similar to what you have, but may be a bit less bulky.  An alternative to consider is a Deutsch Removable Bridge.

Usually a removable denture is converted into a fixed bridge and the flange as well as the palate is removed. This may seem bulky now but this is to prevent fracture of the temporary bridge. The final prosthesis should be less bulky and polished to high shine. 

The temporaries are fabricated before the extractions, thus they have a tendency to be more bulky than the final product. They are almost always not as smooth and comfortable as the end result.

Hi and thank you for your question:Typically the final prosthesis is less bulky and more polished than the temporary denture.Good luck with your new teeth!!Dr. Juan C. ArroyoOral and Maxillofacial surgeon

Hi:The temporary you are wearing was fabricated prior to extraction, healing.   The final should be a lot less bulky and much more comfortable.Best,Dr. Maddahi

In general, with the traditional All-On-4 procedure in which a denture is converted into a bridge chair-side on the day of the surgery, the temporary teeth tend to be bulkier than the final teeth.  This is due to the fact that most All-On-4 temps are all acrylic and need some bulk for strength.  There are other ways to make All-On-4 temps that can be thinner, but that is for another discussion.
Regarding the location of the screw holes in your bridge, they will not change too much unless your doctor changes your abutments (the parts that screw into the implants). 
I would let your doctor know about your concerns before moving on to the final set of teeth to see if he/she can make the changes you desire.