Hi Sharkskin,
Welcome to the forum. The folks here are among the friendliest and most knowlegable I've ever met. You're in good hands. WWI tank kits are not nearly as popular or as prevalent as WWII, so good luck in finding any kits. Your "wino tank" sounds like a real collector's item. With your 38 years of modeling experience I'm sure you'll do it justice.
I do have a couple of suggestions for you though. OD is a boring color for me too, so I really enjoy German armor and the camoflage schemes they employed. Plus German tanks also had zimmerit applied for a few years during the war, which is another plus.
Armor modeling is much more forgiving than aircraft modeling. Armor is supposed to be messy, dirty and torn up, so if you make a "mistake" you can usually cover it up and turn it into something good. I recommend trying your hand on a couple of easy kits, just so you can perfect your techniques, and then show off your skills on that rare Panzer MK IV. As for a Sherman variant, I'd recommend either the Sherman Firefly with the 17 pounder gun, or the Sherman M4E3E8 "Easy Eight". Both of these kits will test your skills in the areas of research, creativity, scratch building, and extras you can add. If you're looking for extra goodies, you can always add additional armor plates, periscope guards, wire hatch handles, and a real antenna.
German armor offers multiple variants for every model of tank, and within those variants, you can vary the paint schemes and whether or not you can apply zimmerit.
Don't forget aftermarket metal barrels and Fruilmodel white metal tracks!
Good luck!
Okieboy