Werbil
If it were up to me, same answer as before. Do a 'proper' aerostudy, consult 'properly' with those who use the facility. Sure, if a location shows a higher level of service is desireable, then a CTR/A tower/app service well and good.
Some of the things I would ask:-
Is the IFR & VFR traffic density at Proserpine sufficent to warrant CTA/R?
Beyond traffic density, is approach complexity, topography, Wx, etc going to raise an elevated consideration for third party clearance services?
How extensive [if at all] is the track record of CFIT or related incidents and accidents [that could have be averted by having ATC at PSP] ? Is there justification?
Obviously we cannot have radar ATC holding the hands of IFR at every possible airport they might use! So where are the lines in the sand?
Come to think of it, are any other IFR operators requesting CTA D, E, C at G locations for CFIT protection?