Like this, you mean?

   
    Colemak Angle(Z)Wide(Qu) on an ANSI keyboard; DreymaR's suggested fingering

You've seen my suggested Polish layout in the sig topics? The problem is the Żż key which an ANSI keyboard will lack. You could use AltGr with Zz but it may be annoying.

   
    Colemak[eD]-Polish 'Unified Symbols' layout (AngleWide), with fast-access accent dead keys on the bracket keys

I cannot really advise you about DH-mod or not. I love the DH mod, obviously, and it didn't take too long to get used to once I was used to Colemak.

You've seen Tarmak too, I hope?

What exactly do you wonder about with the Extend layer? "Why I've arranged it that way" is a bit unspecific. ;-)

My point is that having the much-used accents on an unshifted key makes it very fast to hit the accent and then the letter, like a normal bigram. In contrast, AltGr presses can twist the hand a bit and require you to keep one key down while hitting the other which can be annoying when typing very fast. Some AltGr presses are quite okay, but others are a bother. AltGr+N for instance, is very easy!

One of the world's fastest typists, Sean Wrona, once said that he preferred using Sticky Shift (like a dead-key Shift) to the normal shift when typing really fast. This illustrates the point that using a modifier key is more complex and potentially error-prone than hitting two keys in succession.

Using a Wide mod makes AltGr presses much easier, as the right-hand thumb rests closer to the AltGr key so there's less twisting of the hand.

That's what my enthusiastic Extend topic is all about. The remapped modifiers are a big part of what makes this so powerful!

I'm Norwegian and we have both some AltGr mappings and some dead key accents on our keyboards. I think that dead keys are nice when you have many letters using the same accent, but if those letters are a bit common the dead key needs to be easy to hit. For my standard layout I use AltGr+symbol keys to get the accent dead keys, but since for instance Czech and Polish use the same accents a lot their keys need to be easy to hit. That's why I put them on the first shift level in my Polish layout.

It may feel weird at first if you're not used to dead keys, but keep in mind that it's more like hand writing (where you'll write the accent and the letter separately – albeit in the opposite sequence!) and Linux Compose (where you can usually write the two parts in any sequence), it's not more key presses but probably a little more ergonomic and it lets you overload letters more easily (in Polish, this applies to ż and ź which both compete for the Z key with the AltGr approach).

Oo, tingly feelings! How nice! :-D

Yes, you can remap each layer in a PKL layout. But the Tarmak layouts are remapping using 'VirtualKey' mappings which use the system mappings and just move the logical keys themselves around. If you look into one of the layouts with [eD] in them you'll see how full key remappings are done, and you may mix VirtualKey and full mappings in the same layout freely.

I haven't included any full-mapped ANSI layouts it seems, but what we need to know is that the slash and tilde keys have the VK names OEM_2 and OEM_3 on US/ANSI boards (it's different for Euro/ISO boards – see the layout.ini files if you're interested!). Furthermore, dead keys in PKL are handled by numbers so you'll need to copy lists of the dead keys you want from one of my [eD] layout files and, if you want to do anything fancy, take note of which number corresponds to which dead key!

The lines you need for your layout.ini file (replacing the lines you've currently got for the two keys) will look something like this:

SC029 = OEM_3    0    `    ~    --    dk14    ≈    ; QWERTY `~ - dk_tilde, US/ANSI
SC035 = OEM_2    0    /    ?    --    dk19    ¿    ; QWERTY /? ; dk_stroke, US/ANSI

So you'll need to copy my dead key list from one of my layouts, at least up to dk_19 (so take the whole list – it's a lot of lines but just paste it into your layout.ini file at the end). Otherwise you'll have to renumber the ones you're going to use. Now, to swap / with the ~[dead] change the above lines like this:

SC029 = OEM_3    0    `    ~    --    /    ≈    ; QWERTY `~ - dk_tilde, US/ANSI
SC035 = OEM_2    0    dk14    ?    --    dk19    ¿    ; QWERTY /? ; dk_stroke, US/ANSI

Make sure you get it right with respect to tabulator white space! Use an editor which shows white space (like NotePad++) and look in the layout.ini file how it's done.

Good luck!