We had a CR-V and when I first quit my job to stay home with my 2 kids (then ages 2 yrs and 4 months), I also kept another 4 month old. I fit 2 infant carriers and a forward facing toddler seat in the back seat. For whatever reason, the toddler seat needed to be on one side for it all to fit. It was tight back there, but it was the only way I could get out of the house for anything like a bank run, library, etc. Our CR-V was a 2001, so it didn't have the LATCH hooks.
Have you tried not using the LATCH system and/or switching around the order of the car seats? Also, Babies R Us will let you take display models of car seats out to your car to try them out (with a store associate watching closely, of course!). The backless boosters might be narrower and work better for you.
I totally understand not wanting a car payment!
Since our CR-V was a lease we ended up returning it at lease end a few months after I became a stay-at-home-mom, then bought a Dodge Grand Caravan that was a lease-return. So, we didn't do the "carseat squeeze" for long. We got our van from Superior Leasing (http://www.superiorleasing.com/). They are somehow connected to D & M auto leasing to sell their lease returns. Their prices are really great and the cars have low miles and are in great condition. We've had our van for 2 years without a problem. Also, we didn't have a car payment for long. We had some credit from the Honda, some cash in savings, then put the balance on a 0% interest credit card. We paid it off in about a year. Anyway, if you're interested, we can send you the name of our sales guy. He leased us the Honda 6 years ago, then sold us this minivan.
I know there are sooo many people who are anti-minivan, but these things were made with kids in mind. It's so easy to load and unload and stash all the kids' things. There are cup holders, A/C vents, power outlets, etc. exactly where we need them. And the sliding doors are wonderful!
Yes, it was weird giving up the Honda (it was my 3rd Honda) for a Dodge, but on reading reviews, even called Ed Wallis (he does a radio talk show on KLIF about cars), most cars have about the same ratings and performance these days as far as mechanical integrity.
Good luck!