"the forges at Blizzard are hot, but for some things you will just have to wait longer"
Or something like that, isn't it?
Between lines on Blizzcon it was said there will be a PTR for season 16 and there will be "something not seen yet" as bonus in the season.
I don't have any high hopes even if that is true, since for a half decent patch, PTR should already be up.
If we are talking about Americas CR 72 then,
NumLock Devour, hit Frozen Lands at the start of the rift to stack up defenses and just wreck mobs on the way.
Here my clear for reference:
If we talk about EU rift it is even easier (though slower) than the NA CR. Video here (first try):
If I got your question right - number of levels is preset; sometimes you have just one, sometimes 10 - depending on the size and mob density of each level. And, it doesn't matter where (what level) you kill the Rift Guardian - it will not do anything regarding chance of a goblin pack spawning.
it would help if you would tell us what the main issue is - missing damage or survivability?
Also, pls link your current gear (as you might have to re-roll a thing here and there) - you can do it directly from battle.net - like my seasonal Necromancer:
I just glanced over your toon - you are missing a lot of CDR for Akkhan Condemn (if possible re-roll all that resource cost reduction into CDR - the goal is to get to around 56-57% CDR for permanent Akkarat Champion).
Regarding the progress, a combination of everything - rifts, GR's and bounties for as long as you find it enjoyable. With the shards you get from those activities try to get ancient items that you will augment later on.
Diablo III: Challenge rift 70 - Americas:
Diablo III: Challenge rift 70 - Europe:
Neither of them is to hard, for NA one it is recommended to build up Sweeping stacks as fast as possible (for defense) and hold them through the whole rift.
Diablo III: Challenge rift 68 - Americas:
Diablo III: Challenge rift 68 - Europe:
Both are very similar, shouldn't be to hard.
Diablo III: Challenge rift 67 - Americas:
Diablo III: Challenge rift 67 - Europe:
Both are easy and done on first try.
Diablo III: Challenge rift 66 - Americas:
Diablo III: Challenge rift 66 - Europe:
Both are easy, cleared on first try - could have used Wrath of the Berserker more often (for both, EU and NA), was kinda keeping it around for Rift Guardian. Get your mats and shards easy
Diablo III: Challenge rift 64 - Europe:
Diablo III: Challenge rift 64 - Americas:
EU one is easy, NA this time around a lot harder. Good luck
Diablo III: Challenge rift 63 - Americas:
Diablo III: Challenge rift 63 - Europe:
Both easy, done on first try. And yes, I played the EU one badly.
Diablo III: Challenge rift 62 - Americas
Diablo III: Challenge rift 62 - Europe
More detailed Pchild guide for Americas one:
Diablo 3 - Challenge Rift #62 - Map and Elite Locations
Diablo III: Challenge rift 60 - Americas:
Easy Vyr set-up, shouldn't have issues.
Diablo III: Challenge rift 60 - Europe:
Strange Firebird Meteor build - try to Arcane Torrent at the same time when you do meteors - as it will buff meteor damage, too.
Diablo III: Challenge rift 58 - Americas:
Diablo III: Challenge rift 58 - Europe:
Interestingly different this time around, but not to hard.
And, Pchild guide for America's if you need more details:
Diablo 3 - Challenge Rift #58 - Video Guide with Map and Elite Locations!
Necro This week!
Diablo III: Challenge rift 57 - Americas:
Diablo III: Challenge rift 57 - Europe:
Both of the rifts are some awkward LoN Multishot combinations. Needed multiple tries to do them both, mainly due to pathing. If you follow the path I took you should finish them on time but probably not break a record.
Here also the Americas guide from PChild, if you need more detailed descriptions: