I think it'll be good.
I would do a minimash with 1# of 2-row and 1# of Munich or Vienna to replace 1# of extract. The tripel is nice and light so a little bit of darker base malt really comes through and gives a nice flavor and color.
You want about 1:3 IBU:OG ratio for a tripel. I think the single hop addition is sufficient. I used 2oz Mt Hood for bittering my tripel and came out around 30 IBUs. My OG was 1.090.
Tripels take forever in the fermenter. I don't remember how long mine was in the primary but I think it was 4-5 weeks. It was a good 3 1/2 weeks before the yeast activity completely died down. These Belgian yeasts can be really slow finishing with a high gravity.
I would pitch 2pkgs of dry yeast for a beer this big. Starters are more expensive and more hassle than just buying more dry yeast.