I think plaques would be ok. I think the concern is that what if others started moving to other physical prizes in an up-the-ante kinda competition where there is more monetary worth to the prize? I think we would have to say that only plaques costing up to some X reasonable amount is ok and not allowed any other form.
In regards to the icons, there are at least a couple of different issues. One, I'm not sure about the capabilities of creating so many different icons and along that line, if it is doable, how long it would take for Kestas or jmo or Oli to create something like that, particularly since we have other features that we think should be implemented first like the preview feature, reliability rating, colorblindness. Two, what if other people wanted icons for other tournies or for ghostrating and sub-categories? We would either have to be willing to create additional icons on a regular basis or say that there is only ONE tourney worthy of icons per year. We have no capabilities of doing the former (and there are other reasons why we don't want to do it anyway) and if it is the latter, it would have to be a site-wide tourney where anyone can enter, which has a host of issues like NMRs, CDs, metagaming and multigaming and the logistics and maintenance would be very very high for the TDs as well as the mods. Based on our experience with prior tournies, this would be a nearly impossible task to do well and would require substantial resources of the entire mod team. These are just two main issues and I can go on.
From the most practical point of view, I think we can do donations as entry and plaques for the winners and I can put up the results on my profile. I can also talk with Kestas and Jmo about creating a new page where we can list the winners of tournies by years and we can update that after each tourney.