Interesting that you mentioned the "bumbs" showing through the gelkote. My boat (a Tayana 37 like yours) is a 1985 vintage and has for the past several years have shown small dimples or "bumbs" in the groves. I know that I have a very thick matt layer on the boat bottom so maybe those bumbs were not caused by thermal cycling. Now if I can figure out a way to be rid of them. The hull gel color is a light beigh and I've seen similar "bumbs" on other T37s with white gels.
A totally different situation on Tayana boats ... probably poor mix of OEM gel/MEK ratios / dirt / and someone forgot to drain the air compressor before spraying the gel, plus they probably let the gel fully 'kick' and then waited a day or so before laying matting, etc. .... I 'think' its principally an adhesion problem due a bad mixing, etc. The gel is VERY thick on a Ty37 ... and that may be part of the 'problem'. The good news is that the matting layer is also quite thick.
Im currently sanding down through and re-doing the gel. That beige is ROYAL PAIN to color match as it rapidly fades when 'new' .... arrrrgh. If you consider to re-gel or repair the gel do get a computer color match ... but you have to cut a 3/4" plug from the hull and send it out .... and then deeply sand down into the adjacent gel to remove deeply faded gel and surface oxidation.
BTW - those Tayana pimples will eventually spread, worsen and increase (not larger sized pimples, just 'more' of them) as the gel ages with sun exposure, so do aggressively power-buff and wax often. If you 'get to' these 'teeny pimples' early, you can simply 'pop' them, fill with epoxy and simply spray repair over the repair with new gel. If you let them 'grow', then youre going to have to sand deeply into the faux strake and redo entirely, ... got the tee shirt. Also, Ive seen these Tayana pimples turn into severe alligator cracking of the gel on older ill-maintained boats.
Im doing mostly long distance cruising, I also know that ALL topside paints can't withstand being immersed for very long times (such as being heeled over for for days and days on end)... so that removes any possibility of painting the topsides for me. Ive been down the road of 'topside' paints on other boats, they simply cant be immersed for long term periods without the potential of 'lifting' ... all the paint tech data states this, and I had to find this out the 'hard way'.