For the given cost and time efficiency, doing the whole service is a good measure. Like any mechanical component, it can go any time so it's no guarantee, the odds are in your favor. When I had my timing belt service, the idlers, water pump, and cam seals were also done.

How are the fluids? Tranny, coolant with thermostat swap and the differential?

 

Fluids are fine; I just did the 60K service myself back in May. Drained/flushed/filled coolant, changed oil and filter, drain and fill on transmission (will do this on each of the next few oil changes), drained and filled differential, replaced brake fluid and bled lines. I did not replace thermostat.

Can anyone speak to difficulty of cam seal replacement? Does anyone have a DIY tutorial on it?

 

What would be interesting but not one mention of it; no one shows us what these belts looked like at 90k miles. Are they brittle, cracked and worn ready to fail at any moment or are they supple and still funtional?

I'm wondering how much conservative engineering is built into this maintenance interval. I've got a 2000 Tundra with the 1UA-FE at 92k miles. So I am on the bubble for re[lacement and will address it this summer. And I'll post pix of the parts. My bet is the belts will look perfectly fine.