Oh, yes, you have curtain airbags, it's a very safe car, and I'd have no concern with an 8 year old in a window seat, in either a backless or a highback booster. (The latest study shows that backless boosters are as safe as highbacks, though if she's a car sleeper and needs extra support, the highback is a great choice).
Britax Parkway and Chicco Kid Fit are cushy choices that become a backless and can be left LATCHed in so they don't fly around when unoccupied. Recaro Performance is a little bulkier but very nice for older kids, it cannot be used backless later, and the LATCH does not tighten (LATCH doesn't need to be tight for safety, so they leave off the adjuster piece on their straps).
The word 'Booster' really gets thrown around on a lot of seats! Some have a harness (Pinnacle/Frontier/Argos etc) and some don't (Parkway/Recaro Performance/Kid Fit/Turbo/Big Kid Amp/Right Fit...etc)... no need for a harness for an 8 year old, unless she has some special needs that require a lot more restraint (though pretty much ALL kids need to be reminded to sit properly in their seatbelt, once you are done with the harness, even teenagers
)