HBB problems in 2002 Forester

I just moved my DD to a booster in DH's 2002 Subaru Forester. 2002 was the last year of the old style Foresters. Anyway, the seatbelt is set quite a bit forward from the seat, and doesn't play nicely with the belt guide on the boosters. I tried both the Safety Surround Turbobooster and Parkway SGL there. I mean, it's okay, but DD has to really tug at it to get it out, and then we have to make sure the belt is feeding back in correctly and not getting slack in it.

So I'm kind of displeased with the fit. From what I understand, the Turbo is one of the most compatible boosters, and that seat has the problem too.

I'm tempted to just go with a backless there, but not sure...

I like that with a backless I know the shoulder belt will fit flat against her body with no slack, but I'm worried about the lack of side impact protection.

DD can sit well in a backless, and this is not a vehicle she would ever fall asleep in (mostly used for DH to take her to and from school and activities).

We are out of harnessed seats that fit DD. Since my younger child is nearing 35 lbs, I had to pass along both our Radians to him so he can stay RFing.

WWYD? Should I just not worry about the less-than-smooth belt movement on the HBB? Or should I go for a LBB and not worry about the lack of SIP?

Bump... any advice?

Maybe I'm too wordy... short version:

HBB shoulder belt guide doesn't play nicely with the seat belt in DH's Forester... should I just try and make it work or put DD in a LBB?