Question on shimming bathtub flange

[NTM]

I just put in an alcove bathtub and I am ready to shim and screw the flange into the studs. However, the front of the tub has about an inch gap between flange and studs. I can put about two shims between the gap. Should I use something else, or is double-shimming okay?

Also, what size screws should I use? I have both a box of #6 and #8 SPAX 1.25 inch construction screws (zinc coated). Will either of these work?

Thanks in advance for the help!

 

[Terry]

You're going to need to shim that wall too aren't you? Being shy by one inch is quite a bit.

 

[Sponsor]

 

[NTM]

You're going to need to shim that wall too aren't you? Being shy by one inch is quite a bit.

Heres a few pictures.

 

[NTM]

I could just shim the back and sides, but use furring strips for the front?