Good resolution!! Yes a 2 board solution would work well with the sail quiver you mention, as you are fairly light, it's hard to make one board work with a 3.7 and 5.3. Grip 76 sounds like a good option for most of your sail sizes. And then a board for bump and jump/lighter winds - yes the Triwave 89L is also a good option. But I would really consider also the Mamba if the budget allows it, it does not feel like a big board at all, remember the Mamba/Stubby ranges are all fairly narrow, vs standard outlines. But either way, you'll be fine with the TriWave or the Mamba.
A third option, if you don't want to go over 90L, is the Grip 86, thicker than the best seller Grip 82, it also stills feels relatively small, but has plenty of float and is fantastic with a 5.3 sail. - as you mention you really like to wave-ride, this will be even better on the waves than the Tri or the Mamba. good luck!