I go 1/32
Like others preffer to supersize the trains. 1/32 scale Diecast has a huge following. It is big in agricultural models, tractors, with Ertl producing over many years. They have made a Precision Series which are very detailed and expensive for John Deere and Case. Norscot has produced a few Challanger tractors that are a good value for their detail. They also produce a 1/32 scale construction line which das other imported models from Joel and others. Emergancy Vehicles are made by Code 3 and Franklin Mint, yes high dollar but very nice. Military is covered by Forces of valor which has had a huge production of US armor including M1A1 Abrams Tank, Bradly, Armored amphibious, Missle launchers, Humvees, Tracked & trailered artillery, with detailed plastic soilders from desert storm and Iraq war eras. They also have extensive WWII colection which includes airplanes as does Corgi. New ray produces 1/32 Semi trucks from 60's through modern with varous trailers and loads. They kave also made many cars. There are some Nascar and Indy cars but be careful as some may be slot cars.
1/32 offers the best selection of any the scales for die cast, like 1/29 does for trains. The military equipment actual looks almost to big when sitting on flats. I started collecting 1/32 military over ten years ago and have a full convoy ready for some Military Flat cars! Modern stuff doesn't look right on 40 footers.
1/32 Figures are mostly military. you can find some train stuff but this is an untapped market. Some firemen.
Go to Ebay and Diecast with a 1/32 scale search. You will see what is and has been available. Target, Wal Mart and Toys r Us carry the 1/32 Military stuff as it is released and New Ray trucks and cars at the lowest price. Cat, CASE and John Deere can be bought at tractor dealerships. 3000toys has great selection fair prices and great service.
Remember even though your trains are 1/29 the track is 1/32. There are no 1/29 structures on Market. When forcing perspective using 1/32 to 1/29 makes the trains the leading actor and maintains that WOW factor.
Hope this Helps!