I run a Limited Pro in IDPA and have it setup to be legal in SSP and ESP. It weighed 42.8 oz at the S&W Indoor Nationals last month with Eric Grauffel Xtreme grips, and a single sided extended safety installed. As for the weight, make sure you use the factory plastic base pads because most aluminum ones I know of, will make the gun overweight. For example, my Limited Pro weighs 43.2 oz, when using the Shock bottle base pads from Ben Stoeger's Pro Shop, which is .2 oz overweight.
As for IDPA box fit, make sure you check your gun in an IDPA box of exact dimensions. The Limited Pro is extremely close to not fitting due to the length and I have found slight manufacturing variances in dimensions between the same model Tanfoglio pistols. One Limited Pro might fit and another might not. IDPA allows test boxes to be 1/16" oversize but that doesn't mean the box has to be so although your gun may fit in one test box, it might not fit another. My Limited Pro just barely fit the box at Indoor Nationals and they used a plastic official test box from IDPA which has exact dimensions. The other area of concern besides length, is the width of the Gold Custom extended ambi-safety. This safety setup is way too wide to fit in the IDPA box so you must replace it with a single sided safety. Also note that the Witness extended ambi-safety used on the Stock 2 or Stock 3 will not fit the IDPA test box either and would put your gun into ESP anyway. As long as the part you install comes factory installed on another SSP legal gun, your gun will remain legal for SSP. My research has shown 3 options for SSP legal single sided safeties that will fit the IDPA box. They are, the single sided Gold Custom (used to be installed on the Limited Pro), the single sided EAA Witness extended safety (SSP legal Tanfoglio P21L), and the single sided EAA Witness standard safety (SSP legal EAA Witness). You also mentioned if removing your right side safety on the Limited Pro would still keep your gun SSP legal and the answer is no. Removing the roll pin and right side safety would constitute an external modification and you may not visibly modify any external safety in SSP. As for the slide stop, I am not aware if it is factory installed on another SSP legal firearm but if it is, you should be good to go.
Here is the rule regarding external modifications:
126.96.36.199 SSP Excluded Modifications (Non-Inclusive list):
188.8.131.52.1 Externally visible modifications other than those listed in the Permitted Modifications
184.108.40.206.2 Aftermarket or visibly modified magazine releases, slide stops, safety levers, de-cocking
levers, and hammers.
Hope this helps.