There some Chinese made relays that are supposedly rated for 80A with a 12V coil so they work with OpenEVSE. The wires don't look anywhere beafy enough to use at 80A but appears to work fine at 40A. They appear to be the same relays that are used in EMW's Juicebox. Here's an ebay listing for one.
http://www.ebay.com/itm/1PCS-12VDC-80A- ... xyNThTdwIM
I have used the Chinese relays that the JuiceBox uses. The 80A rating is a poor Chinese joke unless you also need a room heater but they work fine at half that or 40A. They are quite large. I doubt that they would fit in any of Chris's enclosures.
Chris's best option for portable use is the 30A (24A) unit. The two relays he uses are small and the unit is fuse protected for portable use.
Remember it does not really matter what circuit you are plugged into since the EVSE limits the current via the pilot duty cycle. Also the car charger only takes what it needs. An enhanced Leaf will draw 27.5A and not use any greater current. It also follows the J1772 protocol and if it is connected to a 24A EVSE that that is all it will draw even though the car charger could draw 27.5A.
A stock OpenEVSE unit will supply at L1 120V twelve amps. At L2 240V the default is sixteen amps but it can be set in 2A steps to match the available current source.
Remember the car sets the charging current as long as there is enough. A 30A EVSE is the same as the 80A spec max. The car only takes it max current. Thea is why first generation Leaf's were able to use Solid State Relays. Even at 240V they maxed out at 16A.
Currently the only cars that can charge at 40A are Tesla's and Tesla power train cars like my Mercedes B Class or the discontinued Toyota RAV4 EV. Everything else is 30A or less. As I said, An enhanced Leaf charges at 27.5A at 240V.