Very basic designs built at tech level C, which I imagine to be widely available on any planet worth defending. They are intended for local defense and were probably paid for in conscript labor, in-kind taxation, and local currencies rather than C-Bills. All designs are meant to be used in large numbers and supplemented with complementary forces. Even with BAR 5 armor, you might survive a PPC shot, or even two. They are best used at close range because accuracy will be poor due to basic fire control and (presumably) poorly trained crews.
Wheeled Tank
35 tons
chassis: 9.5 tons; wheeled, off-road
engine: 10.5 tons; ICE
speed: 4/6
fuel: 1 ton; 900+ km range
armor: 2.5 tons; bar 5; 18/10/6/18
turret: 1 ton
basic fire control: 0.5 tons
heavy rifle: 8 tons
ammo: 2 tons (12 rounds)
doctrine: Use with Scorpion tanks (standard and LRM). Drive at the enemy until you are in close range.
If the enemy is shooting you, they aren't shooting your precious Scorpions.
Alternatively, send a company sweeping through an open area to deny its use to the enemy or to threaten a flank.
Road Tank-Destroyer
25 tons
chassis: 4.5 tons; wheeled
engine: 11 tons; ICE
speed: 5/8
fuel: 1 ton; 900 km range
armor: 1 ton; bar 5; 10/6/3
basic fire control: 0.5 tons
medium rifle: 5 tons
ammo: 2 tons (18 rounds)
doctrine: Keep clear of battle while using roads to get in position behind an enemy's main thrust. Use to harass rear areas or cut off retreating foes.
Best used to get ahead of a pursued enemy and force him to either take you on or waste time going around your position.
In battle, remain behind cover until the enemy is as close as possible then rush out to attack en mass.
Urban Crawler.
25 tons
chassis: 4.5 tons; tracked
engine: 5.5 tons; ICE
speed: 2/3
fuel: 0.5 tons; 900 km range
armor: 2 tons; bar 5; 12/6/4/20
turret: 1 ton
basic fire control: 0.5 tons
heavy rifle: 8 tons
ammo: 2 tons (12 rounds)
doctrine: Use as an ambush unit in cities and forests. Designed for hull-down use in prepared positions. Support with infantry.