If you are broadly in support of the proposals but concerned that they might just be a bit half-baked, but the proposals might get up at the general meeting, you could propose an amendment to the motions.
Usual meeting procedure would say that the chair should only allow motions to amend a motion to be put to the meeting if they would not change the ‘basic intent’ of the motion.
So, let’s say, after some discussion, it becomes clear that the proponents are reasonably confident the proposal should cost no more than $X,000 and happy to have such a limit. Then you could propose an amendment that would add to the motion, ‘…subject to quotes being obtained for the work and the accepted quote not exceeding $X,000’
Similarly, you could add other caveats like ‘…subject to confirmation of X by (a relevant expert)’ or ‘…subject to the structure not extending beyond (some dimension or location or whatever).’ or ‘… and painted to match the building’.
Otherwise, you could speak in opposition to the motion emphasising that you oppose only because the proposals are half-baked. You could encourage owners to vote no on the grounds that the motions should be returned to another general meeting soon once quotes have been obtained and other details provided. If you offer to help develop the proposals appropriately, then your action is more likely to be seen as constructive and more likely to be supported. Thank those who have developed matters this far etc. Remember that the EC are volunteers who might be doing their best at a thankless task.