I'm glad Icon took care of everything!
Yes the sell a longer rear shock for the Tacoma. I run them, they are technically designed for a longer fabtech lift. Mine are valved 25% firmer with adjustable valving. I forget the exact measurements but they're somewhere like 16.8 compressed and 27 extended. With the OME dakars, the icons sat right in the middle of their travel which is perfect. The shock was about 1/2" longer than needed because I used a jack to push the axle down the last little bit to bolt the shock in. I use wheelers superbumps for bump stops in back on top of my flipped u bolts.
You probably also noticed that you'll never hit the bump stops anyway due to the heavy overloads on the spring. I had mine air horn a couple times and felt the rear bounce off the over load, when the bump stop never even touched the frame. Which is why I pulled the overload and ran an extra leaf (but my truck is heavy).
As thethepete said, they may offer different ends for the rear shocks (bottom side). I would be surprised if they didn't have longer ends that would work, even if it's only an inch or so it would be good.
I haven't run other coilovers but if you like the rear icons, stick with them. Especially don't mix icons at one end, with something else on the front. You're already experience why that sucks. But because icons are digressive and other are progressive it doesn't make sense to mix them. Honestly I don't think you'll care that much about adjusting them anyway. I've really only run my front icons at 3 and 4, which is about how they would be valved without adjustments. 3 unloaded and 4 with the camper. I started front and rear (with the camper) at lowest setting. And I would hit bumps and brake heavy etc, and increase just until there was no secondary bounce. Even off road I really haven't messed with them. Unless you're running huge weight changes (ie camper) I just don't think you'll be missing out much. You'd likely be in great shape just running extended length without reservoirs. They will still be light years ahead of the OMEs up front. Run super bumps in front too if you get aggressive at high speed stuff.