Just to clear things up charger wise for you. The FFE's charger works as follows: On 120V it will charge at up to 12A, this is 1.44kW max charge rate. On 240V it will charge at up to 27.5A for 6.6kW max charge rate. So it will charge a little over 4 1/2 times faster on 240.
I wonder about this. I was stupidly playing around with the rapi interface on my OpenEVSE via wifi when a typo I entered caused the max current limit to reset to the default in the firmware (80A, IIRC). The car had been charging for a while when this happened and the displayed current shot up to just shy of 30A and almost tripped the 30A breaker (i.e. buzzing). I suppose my current sensor could be miscalibrated, but I'm thinking the 6.6kw rating may refer to DC output - or maybe it's AC input at 220v). Are there definitive technical specs available for the FFE unit? Maybe some one else with a current display on their EVSE can weigh in. If it's an output rating or 220v input rating, then the car might pull closer to 30 amps (~7.2kw AC at 240v). In that case, max level 2 at 240v could be closer to 5 times faster than level 1 at 120v.
If you buy or build a portable L2 charge station (EVSE) you need to be aware of what current your EVSE tells the car it can charge at. For example some 240V Turbo Cords charge at 16A (3.8kW). The Open EVSE kits can be configured to different current settings. The big thing to remember is you do not want to exceed 80% of the current rating for whatever you're plugged into. For example 240v dryer plugs are typically 30A outlets. 240V oven's are typically 50A. So for these two plugs your EVSE must not exceed 24A and 40A respectively. The 80% rule is there to prevent you from burning down the house. The turbo cord being only 16A will work in just about any 240V outlet you'd ever encounter. It may not be the fastest but it gives the versatility to plug into any 240V outlet and not worry about overloading it. There's plenty of info on here about various adapters and plug types if you want to know more. I was speaking in general terms to keep things simple.
That 80% rule is for continuous loads (~3+ hours, IIRC), which would be the case for a full 0-100% recharge at level 2 but not for the more typical top up. Code compliance and permitting probably require derating for any EVSE installation no matter what the intended usage since it COULD be used for >3h. Exceeding 80% for short periods shouldn't be unsafe but I would worry about forgetting to adjust the current down when plugging in for a longer charge.
If the early 1900's wiring can't accommodate any 240.... then it's time to find a different place to stay during the week!!
I hope it was updated at some point. If it's original pre-WWI stuff, there is probably no proper equipment ground and even the level 1 won't work.