String advice, Pearse #450 set (GDAE), on a Blueridge 70T

[John in PA]

I got a great open-box deal on a Blueridge 70T from Amazon. It's a beautiful instrument, and I'm quite pleased with tone, sustain, projection, etc. As a long-time octave mando player, I wanted to restring and retune to GDAE. I got a set of the recommended John Pearse #450 strings specifically for this tuning on tenors. Sound is just fine with one exception: the G-string is apparently too flexible, as I can press hard at the center of any fret and get almost a half-tone-sharp bend in the note. I need to be very careful when applying a capo or even when chording to be on or extremely close to the fret, or it will off-tune that bottom string. (No problem like this with any of the other strings) I'm interpreting this to mean that I need a less resilient G-string(?)

The G-string included in the set is a .042W, 80/20 bronze. How much thicker should I go to correct the problem? Pearse has single strings available in .001" increments.

[fox]

Buy guitar strings, 12p 18w 30w 45w is what I prefer but you could try a .47 or even .48. for the G.
The blueridge is a bit over braced & is good for 100lb total string tension so a .47 will be safe.
You may also want to check how the strings are sitting on the nut & bridge.