The Combi can take two bikes straight in. The Partner I have seen used but the bike's in at an angle(are there different length versions??).
I can say that I have seen the Old and New Combi, the Citroen Visa van(big box), the old Astravan Combi, VW Caddy's Old and new, the little Suzuki Carry's(small but long) with Trials bikes in them. Others might be worth a try but they would need to be checked for length.