Yes many ways to go. as said go thru the trunk floor to the subframe for the neg cable in the trunk. You want a "continuous duty" type furd solenoid if you dont want the front to rear large positive cable hot all the time cuz if you run it hot all the time you dont need the solenoid but instead run from the batt positive post up to the starter. I ran it hot all the time & We used 1/0 or 2/0 (I forget which) welding cable on the stock car which is overkill & ran it straight from the batt to the starter. By the nature of it welding cable is multi stranded for flexing resistance and very thick insulation (it ain't gonna get grounded out anywhere) and run the alt to the starter relay and the starter relay down to the starter and an ammeter in series in that (starter to starter relay) line. then T from the starter relay to the bulkhed/fusible link. This will show if the batt/alt is charging or discharging. & if no ammeter is used a person could run the alt to the starter and the starter as mentioned directly to the trunk battery same as with an ammeter so all (3) are directly connected in line with large cable then run a line from the starter up to the starter relay and from there a fusible link to the bulkhead/underdash like normal. EDIT the parts house furd solenoids are meant for passing large current for just long enough to start the car (several seconds or so). With it "on" all the time for hours and hours that you are running the car you would need a special "continuous duty" type of that solenoid (they are available) then there is the trunk shutoff the NHRA (& others) require & I ain't up on that deal (which cable it goes to if that matters but I think it does)