Snap vertex without deforming mesh

Summary of Problem

I would like to be able to move vertices, without deforming the surrounding mesh or edge, while snapping to another vertex or move it by a specified unit distance (Not percentage). I am doing my first archviz project and am doing a modern house that has many angles that aren't standard. This means that following the X or Y axis isn't suitable most of the time. Of course, I have done my best to conform to the grid and the axis's

Attempted solutions

In an effort not to cover things I've already investigated, I will outline what I've tried below. Many solutions are almost there but have one glaring drawback that makes it entirely unsuitable for me

Edge Loop and Slide

I have tried "Ctrl + R" to make an edge loop and then slide it, as well as "GG" to get the same end result. This isn't suitable to me as I can only specify a percentage and not the units that are being used everywhere else. You might think, why not just use math to get the same result? Because I want millimeter precision and when dealing with non-even numbers you're going to get some discrepancy. I have looked everywhere to see if there's some way to do this, but oddly it seems to not be a feature of blender. I have no idea how people do any kind of archviz work without a feature similar to this

Temporary Geometry

I have tried creating another object to act as a "ruler" to draw a straight line from the vertex I'm wanting to align to. The problem arises when I want to snap the vertice to the ruler (remember it's at an odd angle to the geometry I'm dealing with). If I was to edge slide as close as possible, there's still a slight deform that occurs when I snap to the ruler (In line with vertice, not to edge). The problem with this idea though, is the moment I want to rotate it to match an angle, it seems there is no snapping with rotation so it will be slightly misaligned no matter how hard I try.

Transform Orientations

I've figured out that you can slide vertices along the normals orientation axis's, which is very useful. I also have used the viewport view in conjunction with "Shift + Num7" to align my view with faces. This would almost be the perfect solution if used with the temporary geometry, but if I try and snap it to a vertex along the ruler, it will snap using the same orientation as is being used to move it - so it will be way off.

Knife Tool

I thought instead of moving the vertex, I could just cut it to the right position from the beginning. For some reason, I can't get the knife to snap to an existing vertice on the initial cut - only after that. I also can't specify the length of lines created so it's pretty much useless to me

Measure Tool

I thought that I could use some sort of "mark" to snap a vertice to when edge sliding, overcomming the lack of ability to specify a measurement that isn't -1, 0, 1. But no, of course when I think I'm there it seems as though the measurement disappears the moment you go to edit vertices. I hope I'm missing something here as it would be a bit ridiculous to not be able to see it in this context. Also, snapping to the measuretool seems impossible - again I hope I'm missing something because this seems like an incredibly basic feature any 3D software should have

I really hope someone can help me. I've spent easily 24 hours on this project and have achieved nothing, as I get so far and realise the misalignment is throwing everything off to an unacceptable degree. Tearing down my work over and over is just driving me insane and making me question my decision to learn Blender... but hey I guess I learn something each time I go through that process.

I agree it would be nice to be able to enter a distance value after pressing G twice.

Method 1

Select the edge your vertex is on, and press Shift Numpad 1, 3 or 7, depending on the situation.

Then set the Transform Orientation to View, press the key to move along the desired axis (X,Y or Z) and enter your distance value.

Method 2

Select the vertex you want to move. press Shift + S and choose Cursor to Selected. Then press Shift + D to duplicate, but don't move it. Then extrude it in a a direction to make a helper edge (along a main axis, close to the edge you want the vertex to move along is probably best) and while doing this, type the exact distance you would want to move your vertex.

Now go to the snapping menu and choose Snap to Edge, check the box Align Rotation to Target, and for the Affect choose Rotate.

Then as Transform Pivot Point choose 3D Cursor.

Now rotate your helper edge, and it will snap to (and align with) the edge your vertex is on. The end of the helper edge will be at right distance. Now you can snap your vertex to that point and delete the helper edge afterwards.

Be sure though, before snapping the vertex, to go back to the snapping menu and choose Snap to Vertex, and for the Affect choose Move. (unchecking the box Align Rotation to Target is not needed but does affect the way snapping responds)

• Thank you!!!!! I knew it was possible somehow, just needed a smart person to steer me in the correct direction! Indeed this is cumbersome, but heck at this stage I'm willing to do anything. Again, thank you so much! Jun 29, 2020 at 3:02
• Be aware, After posting my answer I remembered you can also change the Transform Orientation and do it even faster. And I edited my answer accordingly. (i hope you see this before starting with the cumbersome method) Jun 29, 2020 at 3:04