I've been perusing the forums for a while but hadn't registered until I read your post and the exceptional replies from this community.
I've recently purchased a PleasureWay and have enjoyed many "Austin local" excursions to Inks Lake, South Llano, Fredricksberg, Pedernals Falls, Ft. Davis (I love that place) as well as a few "road trips to nowhere". Enough of those "extended weekend" trips helped me to figure out what I needed (and didn't need) to take with me.
I've taken the Pleasureway (Have you named her/it?) along the route depicted in your blog many times and you will be passing through some wonderful towns getting out of Texas and beyond.
I'm heading out of the Austin area around the same time you are but this time I think I'm heading North-East and perhaps finding myself taking secondary roads to Delaware (or Montana... I haven't decided yet).
I hope you and the Mrs. have a great trip, and I agree with the advice of getting new tires sooner rather than later.
Happy trails -