[RPG] Small campaign to get us (1 PC and 1 GMPC) up to level 2 before starting Lost Mines of Phandelver – is this a good idea

I've played D&D several times before (3.5e), and I'm really loving how 5e sounds. My wife (who hasn't played at all before) is also very interested in D&D, to the point where we now have the D&D 5e starter set (incl. Lost Mines of Phandelver campaign), and we'll probably start playing within a couple weeks, probably a month max.

Though, it will just be the two of us. So, I'll be GM'ing, she'll have her own character, and from whatever she creates for herself, I'll be making a GMPC to compliment her own character (plus some backstory or character stuff for why her character will often take the lead instead of my own).

I've seen many guides on how to handle this very small party situation, e.g.

• Lower the number of monsters in the encounters,

• Single heavy targets, e.g. bosses, should have their total HP dropped,

• Future campaigns should generally be suited to what classes we end up with, rather than being the common any-old-situation-which-a-full-and-rounded-party-can-always-handle,

etc.

There are other suggestions around, such as having Gestalt PCs, i.e. PCs who level equally in two classes, not just one. But as my wife hasn't played D&D before, I think that will be too much, too soon.

Something else I was thinking of was this:

Running us through an introductory campaign first. Something small and generic, probably involving a shared home-village being attacked, leading into a larger thing to do with bandits in the area getting out of control (attacking other villages too, etc.) and needing to be dealt with by the villages (and, prominently of course, us). In the end, this would get us both up to level 2, and maybe even a bit of neat-o equipment, e.g. each of us getting one of: +1 weapon, +1 armor, or other "slightly cool" equipment fit for low-level PCs.

The idea of this is that this can lead into us getting our two-man party together and transitioning into the Phandelver quest. More importantly though, while I'll still be doing things like making encounters have fewer enemies and reducing the HP of bosses, I'm hoping I can do that less, since we'll be a level higher than the campaign is intending for us to be at each point? And if I can do this less, then the campaign hopefully won't feel as "watered down" as I fear it might if I'm having to lower the difficulty so much due to us being the right level, but too few in number.

Basically, my question is this: Is this a good idea?

If so, is there anything specific I should watch out for when doing this?

If the idea of ending up with some cool bit of equipment is good, then is just a bit of +1 equipment a good idea? Or instead of just some +1 equipment, is there possibly some other low-level equipment that would be great for a small party to have (to help sidestep the bane of very small parties: just a couple bad rolls in combat leading to an accidental TPK), but simultaneously isn't overpowered? Or maybe being a higher level will already be a massively-bigger boost than I realise, and the extra equipment isn't necessary?

Or, a different twist, would the good equipment be a good idea, but without the pre-campaign? Put another way, would it be better for us each to start with some item of +1 (or other, mildly magical) equipment, but otherwise not bothering with the pre-campaign and us just starting at level 1 on the Phandelver campaign like everyone else?