I'm glad things are looking up for you! :D Just remember, with practice, prediction and battling gets easier. The next thing you can do is edit your original RMT to include all the Pokemon you've altered/replaced so the raters can better identify if your team need any additional help (if you even feel you need it).
I'd like to mention Gliscor for a moment if you're still looking to replace Infernape.
Gliscor can be devastating on a Hail Team because of its key resistances, excellent defensive, Stealth Rock support, and great synergy with Tentacruel. Not to mention its resistance to Fighting, which on a hail team, never hurts. Now, I noticed you mentioned something about not having access to 5th Gen Pokemon/Items/Moves/Abilities. Ideally nowadays, Gliscor would have Poison Heal. Since that may not be possible for you, Sand Veil is probably the next best option (and you'll have something that can really excel in the Sand in case you encounter a Sandstorm Team).
Gliscor @ Leftovers
Sand Veil
252 HP / 184 Defense / 72 Speed
Impish [+Defense; -Special Attack]
- Toxic
- Earthquake
- Stealth Rock / Ice Fang
- Protect
Just remember that there are many variants of Gliscor, from Swords Dance to Roost to Flying Gem and Fling sets. So if Gliscor isn't working out so well, I encourage you to try different sets to see what can work best for you and your team. If you ever need an example of these sets, don't hesitate to ask us! :3 Anyway, on to the set. Because Gliscor is such an amazing defensive pivot in any team, this set will really let you take advantage of it's abilities as a physical wall. Not only that, but with a solid Toxic+Protect, Gliscor functions as a Stall breaker, often countering its own threats like Rotom-W and Jellicent with Toxic. Earthquake and Ice Fang provide Gliscor with excellent coverage, but for your needs, Stealth Rock has been added. If for whatever reason you decide not to use Stealth Rock anymore, Ice Fang is the secondary move of choice to remove Dragons and opposing Gliscor from the field. Protect ties this whole set together, allowing Gliscor to stall for Toxic damage, heal from Leftovers, and scout.
At the end of the day, Hail teams have serious weaknesses to Rock, Fighting, Steel, and Fire. And it's more or less unavoidable. But, I think you're on the right track here. With some practice, I'm sure you will do just fine. :)