I'm not a fan of blitzkrieg, but I'll left my 3 gold coins.
I don't play any mods, so I have no idea how this would work there. I will skip all that very ealry part of the game when you "get 8 npc, enterpises and so on and so"
0.0 Getting started- party of 100 top tier troops is more than enough to conquer a 1st siedge with normal difficulty settings. Don't be picky, check who is with war with who, there will be fiefs changing the owner, these fiefs are very poorly garrisoned even with good campaing AI.
0.1.If you want to defects and take some fiefs with you- ask your wife "how to improve your standings on the realm". With little bit of luck you will get Resolve the dispute quest with king as one of the sides, And say that king has no right in this conflict - that gives you hudge relations drop with liedge, he shouldn't grant you fiefs from now on, even if you get them alone and even if your renown is decent. This isn't obligatory ofc, but it helps.
0.1.1. Get married.
0.2. During traditional 8npc hunt hire also the other 8 and sent them to gather RtR. It will fix the issue once and for all.
1. You should run honorable character, it's no-brainer here.
2. Take one city for yourself and grant everything else to lords (only honorable ones)
3. Get good (or better yet very good) Surgeon skill.in your party. And some W. Treatment, too.
Once you are ready make yourself a marshall and start the campaing. If you are with no war with anyone, chose whoever you like and force their caravan to pay a toll. No one will be sad about it, but you just declared a war.
With good relations with lords, they will always appear when you call them and with v. good surgeon skill they won't even left the army to recover (since the won't get much fatal casaulities). You can run siedge after siedge until faction is no more (I tried that, it seriously works). Lords will always follow you and never left the army. Also don't bother with garrnisons, just give fiefs at the spot to the least devoted lord.
There is many other details that may make things more easy or more hard (get int skills on yourself or on companion? bother with enterprises or not? take tactics/engeenering or not? and so on and so on). You will know better what to do since you will be there and since the answers change under various circumstance and often are just matter of preferences.
p.s. Imo engeenering and tactics are too good to not get them to 10 or even higher but this isn't that common opion, many player don't give a damn about both.
Also, since you plan to do this fast, I'm not sure if buying enterpises in every city still makes sense, they might barely just return their cost.
Epiloque:
If you can use some cheap cheesy trick- totally do it, the cheaper the better.
This picture better explains what I'm trying to say
When you play Good campaing AI that mainly means that every fief will have 300-400 top tier troops in it. Every time you will get to the point when their archers are all dead and their infantry, 100-150 troopers, fine and dandy.
Now.
If you decide to simply charge they will kill (or knock out in this case) hundreds of your troops. Seriously. it's incredible.
You could. "besiedge/unload all ammo/withdraw/repeat as many times as neccessary", but it takes ages. (it's doable and sometimes neccessary, but totaly no fun)
You can also spoil the fact that they don't have anything to throw at you, bait them climbing the ladder back and forth and let your archers do the rest.
This is just one specific cheesy trick that works only with Rhodocks and Swadians. but out of my experience, there is always cheap cheesy trick to help you in need, if you look hard enough.
So good luck and may Gouda bless you
p.p.s I know that's not excatly what you asked for, but I don't know any video from rush conquer.
edit:
I have no idea how and why, but often when I try to give brief, and accurate answer and end up with something likve this post.
I'm probably 40% woman, or someting :S
