If I took my racing more seriously I'd by a high top Transit van like this one http://www.trademe.co.nz/Trade-Me-Mo...-340362631.htm, but only because I don't want to tow.


However you've asked about trailers. I would go with a used horse float. They don't smell like shit, have heaps of room and often large storage compartments.
Pull up the wooden slat floors and put down a sheet of ply wood, add a few tie down points and you have a simple setup ready to go.
You could then add a mezzanine floor of sorts that would sit right up inside against the roof and can could be lowered down onto some stops that sit just above the bikes and be used a bed.