Thank you for this clarification.
I think you're right. Also, RQG pg 423 that says “nobles/priests do not have to tithe income from lands granted to them by their temple” so that would give them additional non-tithed income. I would presume that they must still tithe their non-land income? How would maintaining a retinue count? I would guess that some (within reason) could count as suitable temple expenditure, such as bodyguards, servants and a scribe? Although non-temple gifting may prove challenging.
Scotty's response covers Rune Priests. What about Rune Lords? “Nameless” in the GM’s Screen Pack is a Humakt Rune Lord and an initiate of Orlanth, so it can clearly be made to work.
I assume that they have more freedom (within the bounds of their cult) with respect to their time (as per RQG pg 281) so the 100% of time issue won’t arise.
Financially, RQG p 280 states that they are given the finest possible gear, mounts, accommodation etc, so maintaining a suitable life style should be possible. I assume that they would probably be made up to the noble/priest class wrt income as per RQG pg 423 above. Also the points above about 100% tithe of non-land income and the ability to maintain a suitable retinue would be equally applicable.
As an aside, I'm guessing the rule on tithing not applying to Chief or High Priests or their equivalents is the reason:
a) city/tribe/city leadership tends to come from the clan/tribe/city cult
b) enables said leaders to pay their retinue and spread largesse to their retinue, wider clan etc and to guests, non-tribe adventurers etc.
PS Sorry for the long post - only allowed 1 message/day at the moment, so I need to cram all my thoughts in one go!