Car Seat - check on train or rent?

[TLC1994]

We'll be doing a 16 hr. Amtrak train trip next week with our 7 yr. and 3 yr. old. We'll be renting a car when we get to our destination.

I figured I would check my older daughter's booster seat w/our luggage, but what should I do about the seat for my other daughter? She's almost 4, but only 32 lbs. and short for her age. She uses a Marathon everyday at home, but it's kind of heavy to lug around on the trip. I foresee some complaining from DH...

Anyway, I could use one of the other 5-pt. seats that we have in DH's or Grandma's cars ~ I think they're lighter, plus if something happens to them, it's no great loss (they're older & less expensive). Of course, she'd LOVE to use a booster like her older sister, but I really don't think she's ready quite yet.

Or do I look into renting her a car seat? I've heard both good & bad stories about that.

Does anyone have experience checking their car seat on Amtrak? Any problems? Any suggestions? Do you recommend a car seat travel bag or is it necessary? Would a large plastic bag work too?

Thanks so much!!

[Joolsplus2]

Yeah, just bring one of your spare seats in a bag (big duffel? heavy duty clear plastic?), it really should be fine in the luggage hold, and you won't worry about it. :)