If you do decide to put in a second meter, then the house and the pool pumps stay on E-1, and the second meter is exclusively used for measuring vehicle electricity usage. As mentioned earlier, the current pricing on E-9B is subject to change should the CPUC approve PG&E's Advice Letter 3910-E, which affects both E-9A and E-9B pricing.
Personally, I believe that flat-rate pricing for E-9b will likely get passed in such a manner that its prices will go up. The main "battle" is being fought is based around the proposed changes to E-9A, where a flat rate plan would lead to substantial increases on customers who overall use less electricity (e.g. an estimated 80% increase on my E-9A electricity bill, which would effectively make E-1 cheaper).
While there has been some suggestions to "grandfather" current E-9 customers, that outcome is certainly not guaranteed. Whether or not it's worth risking a potentially expensive second meter installation is a decision that must take these uncertainties into account. Since your husband is an electrician, he may be able to do the required labor at a much cheaper rate than hired labor so that will also make a big difference in calculations.
Keep us posted on what you've calculated out. I'm fairly interested in the outcome.
edit: I suppose submetering (or subtractive metering) should be mentioned as a potential alternative to second meter installation, but the rules for its implementation remain even more unsettled than E-9 pricing. I doubt that it will be implemented any time this year, but I'm sure someone more involved can chime in if they have any more info on that front...