First of all, your 16' antenna isn't going to do much below, say, 21MHz. 14MHz seems to be approaching it's useful limit.
Second consideration is RG-8, not the best kind of coax, even for H.F. It may be worth investing in some RG213 (I know it's a pain to handle).
Third thing to consider is background noise, even with the best equipment you may still be unable to operate from that location.
Noise comes in many forms, flourescent lighting, switch-mode power supplies, even the mains Voltage may have noise on it.
You can try a mains filter or an antenna noise bridge, but even together I think you'll still have problems.