why bother with EASA aeroplane stuff if you've got the heli licenses and only need FAA papers to fly f/w? If you fly where I'm thinking (or vaguely remembering the company's website and fleet), then I'd not spend money on more EASA stuff unless really needed. You'd have generous allowance for the IR on f/w in Europe, but if you can fly small single engine and day VFR, you don't even need the IR or twin stuff just yet, but then, why not do it all, budget permitting, while getting the training for FAA commercial.
I'm envious of your position/job, except maybe location for now. I'd like to be able to fly both rotary and f/w, but it depends on jobs/experience/opportunities to match both and in some countries, flight duty hours/days can be headache more than actual hours in the air.
As mentioned, do get the FAA ATP done by end of July to keep simple upgrade to full FAA ATP. If you're not likely to need f/w instrument, you may consider doing VFR commercial and then 'brush up' on checkride prep doing IFR checkride (if your heli IFR is not enough, get that black/white from Chief Counsel) for the ATP.
In general, budget allowing, no point not doing instrument with twin, as for the twin checkride with IFR privileges, even having ASEL IR, you have to shoot an approach or two in twin/OEI simulation and as mentioned, even if doing the checkride ASEL initial in Arrow/Skylane/172RG, the twin time/training is still OK as complex training for ASEL, even half-way done ME rating, back to complex single, checkride/s, then 'proficiency based' twin add on.
Hell, for the heck of it, if you go to place like Adventure Seaplanes in Minnesota and fly 182 or 206 on floats, either one or both equipped with IFR deck and VP/CS amphibs, so counting as complex time towards ASEL/S commercial, if doing checkride doing both splash and squeaks..
That is, if you fancied something different, yet 3 birds with one stone scenario. I know I'd love to do that, just not yet. I'm dreaming of Sheble's Beech 18 on floats in Arizona. Bit pricey, but what an experience, twin seaplane in piece of history. I'm digressing, ehrm.