SAFETY 1ST Alpha Omega Elite 3in1 Convertible Car Seat

I bought 2 of these seats for both of my boys. I did a lot of searching before deciding on these and I am for the most part very happy with the seats. I love the cushion in these, most car seats are pretty thin and hard on their bottoms for long rides. I have a 2 1/2 yr old who uses it as a forward facing seat, We both love it. It is a larger seat, so there is plenty of room for your child who is supposed to be strapped in one now til they are taller than I am, weigh 80# or old enough to be in about 2nd grade. With the top and bottom latch hook system, I feel like it is very safe and I don't have to worry about it moving around in an accident.
Now for the problem I have found with them. My 6 month old son has to use it as a rear facing seat. It was very frustrating trying to get it latched into place in my car....it has to be fully reclined when rear facing so whoever is riding in the seat in front has thier knees very close to the dash and sitting straight up in order for the seat to fit. Its just a big seat, which is fine forward facing. The only other complaint I have about these seats is the cup holder that can be attached to the seat....there is only a groove for it to rest securely on the left side, which in my car doesn't work because there isn't enough room between the seat and the doors for it to go.
I would and have recomended this seat to others

I have been looking at this one to buy for my son but I dont know if it will fit in our Nissan Frontier King cab. We have to drive to Az from WA and I need a car seat for the truck. I need something that would sit at an 90 degree angle and is flat on the bottom. Can anyone help??