I had planned to do this last winter, but soundproofing and interior work ate up my free time.
So, since I have a simple mind:
1) insulate, insulate, insulate. Access panels and center spline area.
2) Fan off - nothing except what leaks through system
3) Fan on, AC off, recirc off - outside air comes in. Can be heated. Natural "cool" air enhanced by steam heat from front radiators.
4) Fan on, AC off, recirc on - draws air in from cabin footwell vents, but most of that is blocked on US cars. Can be heated. Cooling - not really; again, subject to general conditions,and whatever leaks there are.
5) Fan on, AC on, recirc off - fresh air from nose ducts. Can be heated (when it's cold but damp, reduces condensation). Can be cooled, but difficult because Lotus system not as efficient as big old uhmurrican cars.
6) Fan on, AC on, recirc on - cabin air, not much because of blocked vents. Can be heated or cooled. In theory, will become more humid (many cars have timer on recirc to prevent humidity and carbon monoxide buildup. Lotus probably not that well-sealed.). But, theoretically maximizes AC because not drawing in hot air from outside (see "Max AC" on many cars.)
Need to unblock footwell vents though or flow is limited.
7) If you unblock footwell vents, then outside air is always coming in when system is on? Some goes through heating or cooling devices, but some just comes right in? Is that the downside? I guess this is happening even now, if recirc is off, because they're not completely sealed?