When I do dumbell rows I struggle with 105 lb dumbells to get 6-8 reps. I need to get straps because I have some nerve damage that messes with my grip, so my grip gives out before my lats. I just started up barbell rows again and am doing about 195 lbs for 6 reps so I am trying to work up in the weights. I am very weak in pullups so I need to work on that!
Sometimes I have to put the weight down as you said to complete another rep...sort of rest/pause reps. But I don't want to overtrain and need to get back to periodizing more reps and sets.
Straps are fine if your grip gives out first, don't worry about that too much. You can work on rebuilding grip separately at a later time if need be, but don't let your grip hold you down from getting ahead on your back work!
I definitely recommend working on pull-ups - it might take a few months to get strong with them, but they usually click pretty well one day and things go from difficult to much easier. Work on negatives, assisted pull-ups (use a band wrapped over the bar and under your knees, or, use a bit of push off the toes on reps), etc., and as you get to being able to do sets of 4-5 easily enough, start adding some weight to them. Good stuff!
The rest/pause rep stuff had really helped me get to new levels for back and shoulder work over the years. Never felt like I was overtraining from it, if you haven't given it a shot to really incorporate them, definitely try it for a while. I don't recommend making most of your sets go that route, but if you were doing, say, 5 sets of 8 on rows, if the last 2 sets required you to pause and take a few breaths on the last 1-2 reps, that's perfectly fine. I wouldn't stress much about overtraining unless you're REALLY worn out and have been feeling drained, as a few extra reps forced out here and there shouldn't do any harm.
The last few months I have moved back to weighted dips and overhead dumbell presses but I tend to do them the same day as chest otherwise I fear overtraining if I do shoulders one day and chest another since you hit shoulders hard when you do chest!
See, I've always felt the opposite. If you're doing chest and shoulders on the same day, ONE of them is going to suffer, and that's whichever you do 2nd in the sequence. I've never known anyone to be stronger on their shoulder pressing doing it after benching than when they put it on a day by itself or with other non-interfering lifts. Remember, the delts and triceps are smaller muscle groups and recover fairly quickly, so even having 2 days off between chest and shoulders could allow plenty of time for recovery. Worth a try if you haven't gone that route before, again, wouldn't stress too much about overtraining unless it's something that's coming due to general excessive training and being too run down from everyday life.
You mention wide lats. But watch this clip? I know my last are as wide if not wider. I would need to get a nice back shot.
That could be it, without a back shot to show a lat spread, it's impossible to tell just how much work they'd need. I could just see a bit for improvement on overall thickness, but again, that's easily enough fixed with rows, pull-ups and deadlifts, so time will always take care of that. But, if you have a good lat spread, then that's one less concern, just keep working on general size as the bigger you will be, the more beneficial for how it will work in your favor on stage!