With that much driving, I wouldn't recommend trying to tell if the oil is still good based on look and feel. If you're wrong, you're driving on bad oil for quite a while.
I'd suggest having the oil analyzed at 7k miles (after a 5k filter change) to verify it is still good. If so, have it tested again at 9k miles. You may be able to extend the replacement intervals which will save you some decent $$ with as much as you drive. You also may want to consider the PAO extended life oils like Amsoil or Redline.
I use Blackstone Labs (
Blackstone Laboratories) for my analyses. Cost is ~$25 (extra $10 for TBN analysis) plus a few $$ for postage. No affiliation, just a happy customer. Results e-mailed a couple days after they receive the sample. They'll mail you sample cups if you ask.
I've not yet had the oil on my Tundra tested (only have 6k miles on it) but have the oil on my race car tested frequently and wife's car annually.