I like the idea of rewarding TDs. If not giving them credit for their event (whether they play or not) in the standings, then how about a second tier invitation to finals? Same old same old invitation system, but after a period of pre-reg (a week, a few days, whatever) for those earning invitations the old fashioned way, the next wave of invited players is the TDs. At the very least, you're filling in the field where the players aren't.
Or perhaps a TD only event separate from finals? Just something to gather the season's TDs together to show some appreciation and perhaps allow for some idea sharing and direct feedback on the series as a whole. Competitive rounds optional but surely appreciated.
The PDGA is doing this now for its TDs and volunteers with the
Directors Cup. It's a free event just for TDs featuring a two round tournament, seminars, food, and plenty of time to socialize and share thoughts with other TDs and of course, the PDGA staff themselves. They started the event last year and their goal is to have it branch out into regional events in the same vein (so we don't all have to trek to GA every time).