If you can afford a tiagra just make your chef fish
Good call on tld 30 just about indistructable gears. If you dont want to spend that much get a penn 9/0 at the first water front pawn shop you come by they're tough as .... and easy to work on and get parts for. You can use the rod clamp and clamp the reel to the base of you stern rails If your worried about a marlin taking you rail off use light leaders 60# You can run it just like the hand line. only you have a drag and a good way to store the line. I still prefer a rod. get a few black and purple , blue and white, blue and pink Orange and anything skirted lures I like Islanders rigged on seven strand wire you wont get as may bites on wire but you will loose fewer lures. bright colors on sunny days dark colors on cloudy days. you can't drag them too fast. remember fish with burst speeds of fifty to seventy mph will have to slow down to hit anything going less than 12 knots. 4.5knts is ideal for mackeral,tuna and dolphine. 7.5 is bill fish speed wahoo will hit anywhere from 4.5 to 15knts. put the lure out were it's riding on the face of the wave not the back of it and its ok if it jumps out of the water regularly as long as it doesnt foul its self. We catch alot of fish on Yozuri bonitos in orange and black its a diving plug so will work better on a rod. at 6 to 7 knts It will have to be rerigged often. and the big ones will probably take speed off your boat
your lures dont have to be the big ones either Elaphants do eat peanuts
If you really want to get serious learn how to bridle live baits, Five pound tunas work really good. If you want your tuna to grade out at sushi level you will have to bleed out the fish right after you catch it when its done bleeding fillet it off and get the meat as cold as you can as fast as you can. line caught tuna will actually over heat during the fight. the lactic acid and the temp of the fish will actually cook the meat from the inside out if you don't get it chilled down fast it will be mushy. when your handling small tunas turn them upside down (belly up) and they will lay still. a tuna has to swim to live if you hold them still in the water they will drown and if you pull them backward they will drown. so if you catch a haundred pounder and get a tail rope on her just pull her along for a few minutes and then bring it on board.
hope this helps