Thanks for your feedback mickoking, ballaratdragons, davidpretorius, janoskiss, iceman and Wombat_In_Space.
Transporting the OTA shouldn't be too much of a problem - getting around in a Tarago I can fold down the back seats and the passenger-side middle seat giving me a 2,100x500x800 space to put things in and still have three passengers.
The photos on Paul Mayo's site are most impressive, especially for an EOS 300D. Gives me something to aim for ... especially since the EOS 400D has just been released.
I'll try the EQ platform mentioned originally, but what's involved in making your own EQ mount besides 100kg of steel?