I have been in and out of most parts of my 2001 Marlin, as I have added quite a few additions to this boat. I am taking an educated guess here as I have tried to run some electric lines through that area......... You may want to consider installing an inspection plate on the wall of the walk around adjacent to the rail mount so you can get at the through bolts. .... Something to think about... I assume you are asking this question because you can't find a way into that area. ( I know drilling a 4 or 5 inch hole can cause a little anxiety !!!!)...
added the following to my Marlin[/b]....... 2KW inverter ... TV/DVD... blue LED lights in cabin, under gunnel , around hardtop.. added 110v outlet in cabin...added additional 12VDC receptacles in cabin and cockpit.... added engine voltmeters at helm... added house batteries volt gauge at circuit breaker panel...added a 12 volt power supply/charger for house batteries in addition to a new smart charger for engine batteries... got rid of the PIA in tank Grocco head discharge pump and installed an external Jabsco pump..... added two 24'' long SS grab rails at the transom for the euro transom so swimmers could hold on when boarding and not slip into the engines... (because Grady put the ladder on the wrong side !!) ... added two 90' rod holders at the transom..... added a "pulpit" or a shield under the hardtop mounted search light to reduce glare from the fore-deck.