sweet spot for short 45mph commute?

howdy ya'll. Looking into the various PHEV kits and options for my 2006 Gen 2.

We have a 7 mile commute to cover, flat terrain (and can plug in at work), at no more than 45 mph.

Given those stats, which option do you think is best?

I like the idea of the plug in supply kit and being able to lock in EV mode. I'm not sure I like the idea of running the electric motor at 52 mph, seems steep. but I suppose it would be ok, I just wonder about the long term effects.

I can't quite tell the sweet spot of the Enginer kit, and how it would work for this commute. what is the most efficient use of the Enginer kit? is it highway or city?

Then there's calcars, hymotion and the others.

I like the idea of possibly being able to custom configure a kit to our commute, since I have an EV already and am fairly technical. on the surface, the price of a 60ah 2 or 4kwh pack lithium pack with a dc-dc that bumps it up and then allows for 100A or so draws would be just the thing. the price is right on the enginer but it seems a bit underpowered, all the way down to the charger. but PIS might be overkill. it almost seems like what I'm looking for is something in between plug in supply and Enginer.

Anyway, I could ramble on, but in too many words - what do you all think is the best kit to cover my commute?